2025 · practice · Physical Sciences — Chemistry · Grade 11

Grade 11 Physical Sciences Chemistry — Northern Cape practice

Notes

Answer every question. Show the formula, the substitution, and the answer with units. Calculators allowed. These are original practice papers in the style of the province, not a copy of a department PDF.

90 min · 91 Marks · 30 questions

Learn the paper in the app: notes, a marks breakdown, the formula you need, and the board working. You do not need to download it.

Sit it timed Formula sheet

Question breakdown

1.1 · 4 Marks
NaCl is held together by
Notes: NaCl is held together by
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: NaCl is held together by
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: NaCl is held together by. Circle that word — that is the missing variable.
Find
We are required to find: NaCl is held together by. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Metal and non-metal, large electronegativity difference: ionic. Then substitute the given, one line at a time, to get NaCl is held together by.
In other words — as if you have never seen this before
Metal and non-metal, large electronegativity difference: ionic.
2. What do we already know?
NaCl is held together by
3. Which method — and why this one?
Metal and non-metal, large electronegativity difference: ionic.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: NaCl is held together by. Circle that word — that is the missing variable. Find: We are required to find: NaCl is held together by. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: Metal and non-metal, large electronegativity difference: ionic. Then substitute the given, one line at a time, to get NaCl is held together by.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  NaCl is held together by
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  Metal and non-metal, large electronegativity difference: ionic.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  Metal and non-metal, large electronegativity difference: ionic.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  ionic bonds
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
ionic bonds
Copy onto your answer sheet — in this order
Answer: ionic bonds
6. Check it like a marker
Metal and non-metal, large electronegativity difference: ionic.
7. A trap first-timers fall into
hydrogen bonds
1.2 · 6 Marks
c = nV. n = 0.05 mol in 0.25 dm³. c =
Notes: c = nV. n = 0.05 mol in 0.25 dm³. c =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: c = nV. n = 0.05 mol in 0.25 dm³. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.05 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
c=0.050.25=0.2 mol·dm⁻³.
2. What do we already know?
c = nV. n = 0.05 mol in 0.25 dm³. c =
3. Which method — and why this one?
c=0.050.25=0.2 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.05 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  c = nV. n = 0.05 mol in 0.25 dm³. c =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  c=0.050.25=0.2 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  c=0.050.25=0.2 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.2 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.2 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.2 mol·dm⁻³
6. Check it like a marker
c=0.050.25=0.2 mol·dm⁻³.
7. A trap first-timers fall into
0.013 mol·dm⁻³
2.1 · 6 Marks
ΔH = −286 kJ·mol⁻¹ means the reaction
Notes: ΔH = −286 kJ·mol⁻¹ means the reaction
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: ΔH = −286 kJ·mol⁻¹ means the reaction
Before any working — hunt first
Given
Numbers and units already in the sentence: 286 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −286 kJ·mol⁻¹ means the reaction. Circle that word — that is the missing variable.
Find
We are required to find: ΔH = −286 kJ·mol⁻¹ means the reaction. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Negative ΔH is exothermic: heat leaves the system. Then substitute the given, one line at a time, to get ΔH = −286 kJ·mol⁻¹ means the reaction.
In other words — as if you have never seen this before
Negative ΔH is exothermic: heat leaves the system.
2. What do we already know?
ΔH = −286 kJ·mol⁻¹ means the reaction
3. Which method — and why this one?
Negative ΔH is exothermic: heat leaves the system.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 286 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −286 kJ·mol⁻¹ means the reaction. Circle that word — that is the missing variable. Find: We are required to find: ΔH = −286 kJ·mol⁻¹ means the reaction. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: Negative ΔH is exothermic: heat leaves the system. Then substitute the given, one line at a time, to get ΔH = −286 kJ·mol⁻¹ means the reaction.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  ΔH = −286 kJ·mol⁻¹ means the reaction
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  Negative ΔH is exothermic: heat leaves the system.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  Negative ΔH is exothermic: heat leaves the system.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  releases heat
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
releases heat
Copy onto your answer sheet — in this order
Answer: releases heat
6. Check it like a marker
Negative ΔH is exothermic: heat leaves the system.
7. A trap first-timers fall into
absorbs heat
2.2 · 8 Marks
24.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Kimberley lab. 1:1. c(NaOH) =
Notes: 24.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Kimberley lab. 1:1. c(NaOH) =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 24.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Kimberley lab. 1:1. c(NaOH) =
Before any working — hunt first
Given
Numbers and units already in the sentence: 24.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable.
Find
We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
In other words — as if you have never seen this before
n(HCl)=0.100×0.024. c=n0.025=0.096 mol·dm⁻³.
2. What do we already know?
24.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Kimberley lab. 1:1. c(NaOH) =
3. Which method — and why this one?
n(HCl)=0.100×0.024. c=n0.025=0.096 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 24.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable. Find: We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  24.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Kimberley lab. 1:1. c(NaOH) =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  n(HCl)=0.100×0.024. c=n0.025=0.096 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  n(HCl)=0.100×0.024. c=n0.025=0.096 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.096 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.096 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.096 mol·dm⁻³
6. Check it like a marker
n(HCl)=0.100×0.024. c=n0.025=0.096 mol·dm⁻³.
7. A trap first-timers fall into
0.136 mol·dm⁻³
3.1 · 6 Marks
A bond between two non-metals that share electrons is
Notes: A bond between two non-metals that share electrons is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A bond between two non-metals that share electrons is
In other words — as if you have never seen this before
Sharing, not transferring, is covalent.
2. What do we already know?
A bond between two non-metals that share electrons is
3. Which method — and why this one?
Sharing, not transferring, is covalent.
4. Step-by-step working
1. 01 / 07
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 07
  Step B — Write the given in a column
  A bond between two non-metals that share electrons is
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
3. 03 / 07
  Step C — Name the method in words
  Sharing, not transferring, is covalent.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
4. 04 / 07
  Working
  Sharing, not transferring, is covalent.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
5. 05 / 07
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
6. 06 / 07
  Step F — Box the answer with its unit
  covalent
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
7. 07 / 07
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
covalent
Copy onto your answer sheet — in this order
Answer: covalent
6. Check it like a marker
Sharing, not transferring, is covalent.
7. A trap first-timers fall into
ionic
3.2 · 8 Marks · Energy and chemical change
In an energy profile, the activation energy is
Formulas
ΔH < 0exothermicΔH > 0endothermic
Sign of enthalpy change
Notes: In an energy profile, the activation energy is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: In an energy profile, the activation energy is
In other words — as if you have never seen this before
E_a is the hill. ΔH is products minus reactants.
2. What do we already know?
In an energy profile, the activation energy is
3. Which method — and why this one?
E_a is the hill. ΔH is products minus reactants.
4. Step-by-step working
1. 01 / 07
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 07
  Step B — Write the given in a column
  In an energy profile, the activation energy is
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
3. 03 / 07
  Step C — Name the method in words
  E_a is the hill. ΔH is products minus reactants.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
4. 04 / 07
  Working
  E_a is the hill. ΔH is products minus reactants.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
5. 05 / 07
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
6. 06 / 07
  Step F — Box the answer with its unit
  the energy from reactants up to the peak
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
7. 07 / 07
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
the energy from reactants up to the peak
Copy onto your answer sheet — in this order
Answer: the energy from reactants up to the peak
6. Check it like a marker
E_a is the hill. ΔH is products minus reactants.
7. A trap first-timers fall into
ΔH
7 · 2 Marks
At constant temperature, if the pressure of a gas doubles, the volume
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: At constant temperature, if the pressure of a gas doubles, the volume
In other words — as if you have never seen this before
is halved
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
is halved
4. Step-by-step working
1. 01 / 07
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 07
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
3. 03 / 07
  Step C — Name the method in words
  is halved
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
4. 04 / 07
  Reason
  Boyle: pV is constant. Double p means half V.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
5. 05 / 07
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
6. 06 / 07
  Step F — Box the answer with its unit
  is halved
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
7. 07 / 07
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
is halved
Copy onto your answer sheet — in this order
Answer: is halved
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
8 · 3 Marks
ΔH = −394 kJ·mol⁻¹ means the reaction is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: ΔH = −394 kJ·mol⁻¹ means the reaction is
Before any working — hunt first
Given
Numbers and units already in the sentence: 394 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −394 kJ·mol⁻¹ means the reaction is. Circle that word — that is the missing variable.
Find
We are required to find: ΔH = −394 kJ·mol⁻¹ means the reaction is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Negative ΔH: heat is released to the surroundings. Then substitute the given, one line at a time, to get ΔH = −394 kJ·mol⁻¹ means the reaction is.
In other words — as if you have never seen this before
Negative ΔH: heat is released to the surroundings.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 394 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Negative ΔH: heat is released to the surroundings.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 394 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −394 kJ·mol⁻¹ means the reaction is. Circle that word — that is the missing variable. Find: We are required to find: ΔH = −394 kJ·mol⁻¹ means the reaction is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: Negative ΔH: heat is released to the surroundings. Then substitute the given, one line at a time, to get ΔH = −394 kJ·mol⁻¹ means the reaction is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 394 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  Negative ΔH: heat is released to the surroundings.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  Negative ΔH: heat is released to the surroundings.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  exothermic
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
exothermic
Copy onto your answer sheet — in this order
Answer: exothermic
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
9 · 2 Marks
Intermolecular forces act
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Intermolecular forces act
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Intermolecular forces act. Circle that word — that is the missing variable.
Find
We are required to find: Intermolecular forces act. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: between molecules. Then substitute the given, one line at a time, to get Intermolecular forces act.
In other words — as if you have never seen this before
between molecules
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
between molecules
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Intermolecular forces act. Circle that word — that is the missing variable. Find: We are required to find: Intermolecular forces act. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: between molecules. Then substitute the given, one line at a time, to get Intermolecular forces act.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  between molecules
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  They are not the covalent bonds inside one molecule.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  between molecules
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
between molecules
Copy onto your answer sheet — in this order
Answer: between molecules
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
10 · 2 Marks
c = nV. n = 0.03 mol in 0.25 dm³. c =
Notes: c = nV. n = 0.03 mol in 0.25 dm³. c =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: c = nV. n = 0.03 mol in 0.25 dm³. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.03 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
c=0.030.25=0.12 mol·dm⁻³.
2. What do we already know?
c = nV. n = 0.03 mol in 0.25 dm³. c =
3. Which method — and why this one?
c=0.030.25=0.12 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.03 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  c = nV. n = 0.03 mol in 0.25 dm³. c =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  c=0.030.25=0.12 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  c=0.030.25=0.12 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.12 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.12 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.12 mol·dm⁻³
6. Check it like a marker
c=0.030.25=0.12 mol·dm⁻³.
7. A trap first-timers fall into
0.007 mol·dm⁻³
11 · 2 Marks
25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Polokwane lab. 1:1. c(NaOH) =
Notes: 25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Polokwane lab. 1:1. c(NaOH) =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Polokwane lab. 1:1. c(NaOH) =
Before any working — hunt first
Given
Numbers and units already in the sentence: 25.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable.
Find
We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
In other words — as if you have never seen this before
n(HCl)=0.100×0.025. c=n0.025=0.1 mol·dm⁻³.
2. What do we already know?
25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Polokwane lab. 1:1. c(NaOH) =
3. Which method — and why this one?
n(HCl)=0.100×0.025. c=n0.025=0.1 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 25.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable. Find: We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a Polokwane lab. 1:1. c(NaOH) =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  n(HCl)=0.100×0.025. c=n0.025=0.1 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  n(HCl)=0.100×0.025. c=n0.025=0.1 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.1 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.1 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.1 mol·dm⁻³
6. Check it like a marker
n(HCl)=0.100×0.025. c=n0.025=0.1 mol·dm⁻³.
7. A trap first-timers fall into
0.140 mol·dm⁻³
12 · 2 Marks
ΔH = −210 kJ·mol⁻¹ means the reaction is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: ΔH = −210 kJ·mol⁻¹ means the reaction is
Before any working — hunt first
Given
Numbers and units already in the sentence: 210 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −210 kJ·mol⁻¹ means the reaction is. Circle that word — that is the missing variable.
Find
We are required to find: ΔH = −210 kJ·mol⁻¹ means the reaction is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: exothermic. Then substitute the given, one line at a time, to get ΔH = −210 kJ·mol⁻¹ means the reaction is.
In other words — as if you have never seen this before
exothermic
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 210 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
exothermic
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 210 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: ΔH = −210 kJ·mol⁻¹ means the reaction is. Circle that word — that is the missing variable. Find: We are required to find: ΔH = −210 kJ·mol⁻¹ means the reaction is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: exothermic. Then substitute the given, one line at a time, to get ΔH = −210 kJ·mol⁻¹ means the reaction is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 210 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  exothermic
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Negative ΔH: the system released heat.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  exothermic
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
exothermic
Copy onto your answer sheet — in this order
Answer: exothermic
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
13 · 2 Marks
The shape of NH₃ is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: The shape of NH₃ is
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of NH₃ is. Circle that word — that is the missing variable.
Find
We are required to find: The shape of NH₃ is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: trigonal pyramidal. Then substitute the given, one line at a time, to get The shape of NH₃ is.
In other words — as if you have never seen this before
trigonal pyramidal
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
trigonal pyramidal
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of NH₃ is. Circle that word — that is the missing variable. Find: We are required to find: The shape of NH₃ is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: trigonal pyramidal. Then substitute the given, one line at a time, to get The shape of NH₃ is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  trigonal pyramidal
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Three bond pairs and one lone pair.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  trigonal pyramidal
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
trigonal pyramidal
Copy onto your answer sheet — in this order
Answer: trigonal pyramidal
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
14 · 2 Marks
20.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a a national paper lab. 1:1. c(NaOH) =
Notes: 20.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a a national paper lab. 1:1. c(NaOH) =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 20.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a a national paper lab. 1:1. c(NaOH) =
Before any working — hunt first
Given
Numbers and units already in the sentence: 20.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable.
Find
We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
In other words — as if you have never seen this before
n(HCl)=0.100×0.020. c=n0.025=0.08 mol·dm⁻³.
2. What do we already know?
20.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a a national paper lab. 1:1. c(NaOH) =
3. Which method — and why this one?
n(HCl)=0.100×0.020. c=n0.025=0.08 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 20.0 cm³ · 0.100 mol·dm⁻³ · 25.0 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable. Find: We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: n(HCl) = 0. Then substitute the given, one line at a time, to get c(NaOH) =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  20.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 25.0 cm³ NaOH in a a national paper lab. 1:1. c(NaOH) =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  n(HCl)=0.100×0.020. c=n0.025=0.08 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  n(HCl)=0.100×0.020. c=n0.025=0.08 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.08 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.08 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.08 mol·dm⁻³
6. Check it like a marker
n(HCl)=0.100×0.020. c=n0.025=0.08 mol·dm⁻³.
7. A trap first-timers fall into
0.120 mol·dm⁻³
15 · 3 Marks
25 cm³ of 0.20 mol·dm⁻³ HCl vs 25 cm³ NaOH, 1:1. c(NaOH) =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 25 cm³ of 0.20 mol·dm⁻³ HCl vs 25 cm³ NaOH, 1:1. c(NaOH) =
Before any working — hunt first
Given
Numbers and units already in the sentence: 25 cm³ · 0.20 mol·dm⁻³ · 25 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable.
Find
We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 0. Then substitute the given, one line at a time, to get c(NaOH) =.
In other words — as if you have never seen this before
0.20 mol·dm⁻³
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 25 cm³ · 0.20 mol·dm⁻³ · 25 cm³ · 1 · 1. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
0.20 mol·dm⁻³
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 25 cm³ · 0.20 mol·dm⁻³ · 25 cm³ · 1 · 1. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable. Find: We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: 0. Then substitute the given, one line at a time, to get c(NaOH) =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 25 cm³ · 0.20 mol·dm⁻³ · 25 cm³ · 1 · 1. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  0.20 mol·dm⁻³
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Equal volumes, 1:1, same concentration.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.20 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.20 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.20 mol·dm⁻³
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
16 · 3 Marks
A reaction with ΔH = +180 kJ·mol⁻¹ is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: A reaction with ΔH = +180 kJ·mol⁻¹ is
Before any working — hunt first
Given
Numbers and units already in the sentence: 180 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: A reaction with ΔH = +180 kJ·mol⁻¹ is. Circle that word — that is the missing variable.
Find
We are required to find: A reaction with ΔH = +180 kJ·mol⁻¹ is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: endothermic. Then substitute the given, one line at a time, to get A reaction with ΔH = +180 kJ·mol⁻¹ is.
In other words — as if you have never seen this before
endothermic
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 180 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
endothermic
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 180 kJ·mol⁻¹. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: A reaction with ΔH = +180 kJ·mol⁻¹ is. Circle that word — that is the missing variable. Find: We are required to find: A reaction with ΔH = +180 kJ·mol⁻¹ is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: endothermic. Then substitute the given, one line at a time, to get A reaction with ΔH = +180 kJ·mol⁻¹ is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 180 kJ·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  endothermic
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Positive ΔH: the system absorbed heat.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  endothermic
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
endothermic
Copy onto your answer sheet — in this order
Answer: endothermic
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
17 · 2 Marks
NaCl is held by
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: NaCl is held by
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: NaCl is held by. Circle that word — that is the missing variable.
Find
We are required to find: NaCl is held by. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: Metal + non-metal: electrons are transferred. Then substitute the given, one line at a time, to get NaCl is held by.
In other words — as if you have never seen this before
Metal + non-metal: electrons are transferred. Na⁺ Cl⁻ lattice.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
Metal + non-metal: electrons are transferred. Na⁺ Cl⁻ lattice.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: NaCl is held by. Circle that word — that is the missing variable. Find: We are required to find: NaCl is held by. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: Metal + non-metal: electrons are transferred. Then substitute the given, one line at a time, to get NaCl is held by.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  Metal + non-metal: electrons are transferred. Na⁺ Cl⁻ lattice.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  Metal + non-metal: electrons are transferred. Na⁺ Cl⁻ lattice.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  ionic bonds
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
ionic bonds
Copy onto your answer sheet — in this order
Answer: ionic bonds
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
18 · 2 Marks
Water has a higher boiling point than methane mainly because of
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Water has a higher boiling point than methane mainly because of
In other words — as if you have never seen this before
hydrogen bonds
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
hydrogen bonds
4. Step-by-step working
1. 01 / 07
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 07
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
3. 03 / 07
  Step C — Name the method in words
  hydrogen bonds
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
4. 04 / 07
  Reason
  O–H bonds let neighbouring water molecules hydrogen-bond.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
5. 05 / 07
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
6. 06 / 07
  Step F — Box the answer with its unit
  hydrogen bonds
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
7. 07 / 07
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
hydrogen bonds
Copy onto your answer sheet — in this order
Answer: hydrogen bonds
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
19 · 2 Marks
2.0 g NaOH in 0.50 dm³. M = 40 g·mol⁻¹. c =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 2.0 g NaOH in 0.50 dm³. M = 40 g·mol⁻¹. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 2.0 g · 0.50 dm³ · 40 g·mol⁻¹. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
0.10 mol·dm⁻³
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 2.0 g · 0.50 dm³ · 40 g·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
0.10 mol·dm⁻³
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 2.0 g · 0.50 dm³ · 40 g·mol⁻¹. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 2.0 g · 0.50 dm³ · 40 g·mol⁻¹. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  0.10 mol·dm⁻³
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  n=2.040=0.050 mol. c=0.0500.50=0.10.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.10 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.10 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.10 mol·dm⁻³
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
20 · 2 Marks
2H₂ + O₂ → 2H₂O. 2 mol H₂ is mixed with 2 mol O₂. The limiting reagent is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 2H₂ + O₂ → 2H₂O. 2 mol H₂ is mixed with 2 mol O₂. The limiting reagent is
Before any working — hunt first
Given
Numbers and units already in the sentence: 2H · 2H · 2 mol · 2 mol. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: The limiting reagent is. Circle that word — that is the missing variable.
Find
We are required to find: The limiting reagent is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: H₂. Then substitute the given, one line at a time, to get The limiting reagent is.
In other words — as if you have never seen this before
H₂
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 2H · 2H · 2 mol · 2 mol. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
H₂
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 2H · 2H · 2 mol · 2 mol. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: The limiting reagent is. Circle that word — that is the missing variable. Find: We are required to find: The limiting reagent is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: H₂. Then substitute the given, one line at a time, to get The limiting reagent is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 2H · 2H · 2 mol · 2 mol. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  H₂
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  The ratio needs 2 mol H₂ per 1 mol O₂. 2 mol O₂ is excess.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  H₂
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
H₂
Copy onto your answer sheet — in this order
Answer: H₂
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
21 · 2 Marks · Energy and chemical change
Adding a catalyst
Formulas
ΔH < 0exothermicΔH > 0endothermic
Sign of enthalpy change
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Adding a catalyst
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Adding a catalyst. Circle that word — that is the missing variable.
Find
We are required to find: Adding a catalyst. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: lowers activation energy, ΔH unchanged. Then substitute the given, one line at a time, to get Adding a catalyst.
In other words — as if you have never seen this before
lowers activation energy, ΔH unchanged
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
lowers activation energy, ΔH unchanged
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Adding a catalyst. Circle that word — that is the missing variable. Find: We are required to find: Adding a catalyst. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: lowers activation energy, ΔH unchanged. Then substitute the given, one line at a time, to get Adding a catalyst.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  lowers activation energy, ΔH unchanged
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Both directions speed up. The energy difference stays.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  lowers the activation energy and leaves ΔH unchanged
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
lowers the activation energy and leaves ΔH unchanged
Copy onto your answer sheet — in this order
Answer: lowers the activation energy and leaves ΔH unchanged
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
22 · 2 Marks
The strongest intermolecular force in I₂ is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: The strongest intermolecular force in I₂ is
In other words — as if you have never seen this before
London forces
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
London forces
4. Step-by-step working
1. 01 / 07
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 07
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
3. 03 / 07
  Step C — Name the method in words
  London forces
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
4. 04 / 07
  Reason
  I₂ is non-polar. Only temporary dipoles.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
5. 05 / 07
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
6. 06 / 07
  Step F — Box the answer with its unit
  London forces
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
7. 07 / 07
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
London forces
Copy onto your answer sheet — in this order
Answer: London forces
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
23 · 2 Marks
The shape of CH₄ is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: The shape of CH₄ is
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of CH₄ is. Circle that word — that is the missing variable.
Find
We are required to find: The shape of CH₄ is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: tetrahedral. Then substitute the given, one line at a time, to get The shape of CH₄ is.
In other words — as if you have never seen this before
tetrahedral
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
tetrahedral
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of CH₄ is. Circle that word — that is the missing variable. Find: We are required to find: The shape of CH₄ is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: tetrahedral. Then substitute the given, one line at a time, to get The shape of CH₄ is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  tetrahedral
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Four bond pairs and no lone pairs.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  tetrahedral
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
tetrahedral
Copy onto your answer sheet — in this order
Answer: tetrahedral
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
24 · 2 Marks
c = nV. n = 0.04 mol in 0.25 dm³. c =
Notes: c = nV. n = 0.04 mol in 0.25 dm³. c =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: c = nV. n = 0.04 mol in 0.25 dm³. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.04 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
c=0.040.25=0.16 mol·dm⁻³.
2. What do we already know?
c = nV. n = 0.04 mol in 0.25 dm³. c =
3. Which method — and why this one?
c=0.040.25=0.16 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.04 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  c = nV. n = 0.04 mol in 0.25 dm³. c =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  c=0.040.25=0.16 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  c=0.040.25=0.16 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.16 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.16 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.16 mol·dm⁻³
6. Check it like a marker
c=0.040.25=0.16 mol·dm⁻³.
7. A trap first-timers fall into
0.010 mol·dm⁻³
25 · 4 Marks
25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 20.0 cm³ NaOH. c(NaOH) =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: 25.0 cm³ of 0.100 mol·dm⁻³ HCl neutralises 20.0 cm³ NaOH. c(NaOH) =
Before any working — hunt first
Given
Numbers and units already in the sentence: 25.0 cm³ · 0.100 mol·dm⁻³ · 20.0 cm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable.
Find
We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: n(HCl)=0. Then substitute the given, one line at a time, to get c(NaOH) =.
In other words — as if you have never seen this before
n(HCl)=0.100×0.025=0.0025. 1:1 so c=0.00250.020=0.125.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 25.0 cm³ · 0.100 mol·dm⁻³ · 20.0 cm³. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
n(HCl)=0.100×0.025=0.0025. 1:1 so c=0.00250.020=0.125.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 25.0 cm³ · 0.100 mol·dm⁻³ · 20.0 cm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c(NaOH) =. Circle that word — that is the missing variable. Find: We are required to find: c(NaOH) =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: n(HCl)=0. Then substitute the given, one line at a time, to get c(NaOH) =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 25.0 cm³ · 0.100 mol·dm⁻³ · 20.0 cm³. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  n(HCl)=0.100×0.025=0.0025. 1:1 so c=0.00250.020=0.125.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  n(HCl)=0.100×0.025=0.0025. 1:1 so c=0.00250.020=0.125.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.125 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.125 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.125 mol·dm⁻³
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
26 · 2 Marks · Energy and chemical change
Activation energy is
Formulas
ΔH < 0exothermicΔH > 0endothermic
Sign of enthalpy change
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: Activation energy is
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: Activation energy is. Circle that word — that is the missing variable.
Find
We are required to find: Activation energy is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: the minimum energy to start. Then substitute the given, one line at a time, to get Activation energy is.
In other words — as if you have never seen this before
the minimum energy to start
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
the minimum energy to start
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: Activation energy is. Circle that word — that is the missing variable. Find: We are required to find: Activation energy is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: the minimum energy to start. Then substitute the given, one line at a time, to get Activation energy is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  the minimum energy to start
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  It is the hill the particles must climb, not the overall ΔH.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  the minimum energy needed to start the reaction
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
the minimum energy needed to start the reaction
Copy onto your answer sheet — in this order
Answer: the minimum energy needed to start the reaction
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
27 · 2 Marks
c = nV. n = 0.01 mol in 0.25 dm³. c =
Notes: c = nV. n = 0.01 mol in 0.25 dm³. c =
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: c = nV. n = 0.01 mol in 0.25 dm³. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.01 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
c=0.010.25=0.04 mol·dm⁻³.
2. What do we already know?
c = nV. n = 0.01 mol in 0.25 dm³. c =
3. Which method — and why this one?
c=0.010.25=0.04 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.01 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  c = nV. n = 0.01 mol in 0.25 dm³. c =
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  c=0.010.25=0.04 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  c=0.010.25=0.04 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.04 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.04 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.04 mol·dm⁻³
6. Check it like a marker
c=0.010.25=0.04 mol·dm⁻³.
7. A trap first-timers fall into
0.003 mol·dm⁻³
28 · 2 Marks
c=nV. n=0.020 mol, V=0.25 dm³. c=
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: c = nV. n = 0.020 mol, V = 0.25 dm³. c =
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.020 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable.
Find
We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
In other words — as if you have never seen this before
c=0.0200.25=0.080 mol·dm⁻³.
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 0.020 mol · 0.25 dm³. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
c=0.0200.25=0.080 mol·dm⁻³.
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.020 mol · 0.25 dm³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: c =. Circle that word — that is the missing variable. Find: We are required to find: c =. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: c = 0. Then substitute the given, one line at a time, to get c =.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 0.020 mol · 0.25 dm³. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  c=0.0200.25=0.080 mol·dm⁻³.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Working
  c=0.0200.25=0.080 mol·dm⁻³.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  0.080 mol·dm⁻³
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
0.080 mol·dm⁻³
Copy onto your answer sheet — in this order
Answer: 0.080 mol·dm⁻³
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
29 · 2 Marks
The shape of CO₂ is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: The shape of CO₂ is
Before any working — hunt first
Given
Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of CO₂ is. Circle that word — that is the missing variable.
Find
We are required to find: The shape of CO₂ is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: linear. Then substitute the given, one line at a time, to get The shape of CO₂ is.
In other words — as if you have never seen this before
linear
2. What do we already know?
Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
linear
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: no numbers yet — only a name, a diagram, or a worded unknown. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: The shape of CO₂ is. Circle that word — that is the missing variable. Find: We are required to find: The shape of CO₂ is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: linear. Then substitute the given, one line at a time, to get The shape of CO₂ is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: every number and its unit in the sentence. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  linear
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Two double bonds, no lone pairs on carbon. The molecule is straight.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  linear
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
linear
Copy onto your answer sheet — in this order
Answer: linear
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”
30 · 2 Marks
pH of 0.010 mol·dm⁻³ HCl is
How we got there
Read this like a teacher at the board. We go slowly, name every number, and say why we take each step.
Explain in another language · 11
1. What is the question asking?
Read the question twice. Circle the unknown. Underline every number and unit. The paper is asking: pH of 0.010 mol·dm⁻³ HCl is
Before any working — hunt first
Given
Numbers and units already in the sentence: 0.010 mol·dm⁻³. Copy each one into a column. A name without a number is not given.
Missing
After you copy the given, the letter that still has no number is missing. The paper is pointing at: 010 mol·dm⁻³ HCl is. Circle that word — that is the missing variable.
Find
We are required to find: 010 mol·dm⁻³ HCl is. Write that as a symbol on the left, with a question mark, before you touch a formula.
Calculate
What we need to calculate: 2. Then substitute the given, one line at a time, to get 010 mol·dm⁻³ HCl is.
In other words — as if you have never seen this before
2
2. What do we already know?
Copy these onto the left of your page, one per line, with units: 0.010 mol·dm⁻³. Mixing cm with m, or minutes with seconds, loses a method mark.
3. Which method — and why this one?
2
4. Step-by-step working
1. 01 / 08
  Step A — Read the question twice
  Slow down. Circle the word that names the unknown. Underline every number and its unit. Do not grab a formula yet — first decide what the paper is actually asking.
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
2. 02 / 08
  Step A2 — Hunt: Given, Missing, Find, Calculate
  Given: Numbers and units already in the sentence: 0.010 mol·dm⁻³. Copy each one into a column. A name without a number is not given. Missing: After you copy the given, the letter that still has no number is missing. The paper is pointing at: 010 mol·dm⁻³ HCl is. Circle that word — that is the missing variable. Find: We are required to find: 010 mol·dm⁻³ HCl is. Write that as a symbol on the left, with a question mark, before you touch a formula. Calculate: What we need to calculate: 2. Then substitute the given, one line at a time, to get 010 mol·dm⁻³ HCl is.
  Why this step: Do not name the letters yet. First hunt: what already has a number (Given), what has no number (Missing), the word the paper wants (Find), and which formula still contains the missing letter (Calculate).
3. 03 / 08
  Step B — Write the given in a column
  Copy these onto the left of your page, one per line, with units: 0.010 mol·dm⁻³. Mixing cm with m, or minutes with seconds, loses a method mark.
  Why this step: A column with units stops you mixing cm with m, or minutes with seconds. Markers can also see you started correctly.
4. 04 / 08
  Step C — Name the method in words
  2
  Why this step: If you can say the method in a sentence, you will pick the right formula. First-timers skip this and grab the first equation they remember.
5. 05 / 08
  Reason
  Strong acid: [H₃O⁺]=0.010=10⁻². pH=2.
  Why this step: We only do one job per line so a marker can follow the marks — and so you can find a slip without starting over.
6. 06 / 08
  Step G — Sense-check the size
  Ask: is this the kind of number a Grade 10–12 paper would want? A speed of 3 000 ms for a learner walking, or a probability bigger than 1, means a unit or algebra slip. Estimate first: round the numbers and do the sum in your head.
  Why this step: Markers write ‘unrealistic’ in the margin when the method is right but the size is wild. A 10-second head check often finds a missing 10² or a unit that never changed.
7. 07 / 08
  Step F — Box the answer with its unit
  2
  Why this step: A number without a unit is half a mark on a Physics paper, and a marker can miss a Maths answer that is buried in working.
8. 08 / 08
  Step H — What the marker is looking for
  On an NSC memo you usually earn: (1) a method mark for naming the right formula or idea in words, (2) an accuracy mark for substituting the given numbers with units, (3) an accuracy mark for the boxed answer with its unit. Write those three lines even if you are unsure of the arithmetic — blank pages score zero.
  Why this step: First-timers chase the final number and leave the method blank. The memo still pays out for the idea and the substitution even when the last line is wrong.
5. The answer
2
Copy onto your answer sheet — in this order
Answer: 2
6. Check it like a marker
Does your answer appear as one of the options? Do the units match what was asked (m, N, J, °)? If you put the number back into the original equation, does it still hold? Estimate: is the size sensible?
7. A trap first-timers fall into
First-timers often grab the first formula they remember, mix units (cm with m, minutes with seconds), or drop a minus sign. Write the formula in words first: “this equals that, because…”