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P4 General Studies: Air, Burning and Rusting (Paper 2: intermediate)
Tutor Prep Guide · composition of air, conditions for burning, conditions for rusting and ways to prevent rust
P4 General Studies: Air, Burning and Rusting (Paper 2: intermediate)
The second paper practises figures and comparisons: turn percentages into volumes and compare rusting in different places.
Direct answers Convert everything to one unit, millilitres or cubic centimetres, before working out a volume.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: P4 General Studies: Air, Burning and Rusting |
| Level | composition of air, conditions for burning, conditions for rusting and ways to prevent rust |
02 Questions (10 items)
- FoundationAir is about 78 per cent nitrogen and 21 per cent oxygen. How much oxygen is in 100 cubic centimetres of air?
- FoundationWhich gas turns limewater milky after burning?
- FoundationDoes a nail rust faster in salt water or in fresh water?
- IntermediateHow much nitrogen is in 500 cubic centimetres of air?
- IntermediateWhy does a candle in a sealed jar go out?
- IntermediateA nail is half in water and half in air. Which part rusts first?
- ChallengeHow many millilitres of oxygen are in 2 litres of air?
- ChallengeDoes the total mass go up or down when iron rusts?
- ChallengeName two ways to prevent rust and say why they work.
- Error redoA pupil claims a nail rusts in a jar of dry nitrogen. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | 21 cubic centimetres | 100 times 21 per cent gives 21 cubic centimetres. |
| 2 | Carbon dioxide | Carbon dioxide turns limewater milky, which is the usual test for it. |
| 3 | Faster in salt water | Salt speeds up the oxidation of iron, which is why iron near the sea rusts so quickly. |
| 4 | 390 cubic centimetres | 500 times 78 per cent gives 390 cubic centimetres. |
| 5 | The oxygen inside is used up | Burning keeps using oxygen, and the flame dies once the oxygen runs out. |
| 6 | Just above the water line, where water meets air | That band has plenty of both water and oxygen, so both conditions are met. |
| 7 | 420 millilitres | 2 000 millilitres times 21 per cent gives 420 millilitres. |
| 8 | It goes up | The iron combines with oxygen, so the mass of oxygen is added. |
| 9 | Painting and oiling (also galvanising or keeping the metal dry); they shut out oxygen or water | Preventing rust means making sure the two conditions never hold at the same time. |
| 10 | The jar has neither oxygen nor water, so neither condition is met | Nitrogen does not react with iron, and being dry removes the water condition as well. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Then take paper three and use numbers to explain burning and rusting.Tutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.