Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
The Gases in the Air — exam questions
12 original Incandio exam-style questions on the Gases in the Air, 26 marks, about 26 minutes of writing. Each one carries the command word, the tariff and the specification statement it assesses, exactly as a paper presents them. This is an original Incandio practice question, written to reflect the structure and demands of the qualification. It is not an official Pearson Edexcel past-paper question.
This is the practice set for The Gases in the Air — the lesson that teaches it. Read the lesson first if the idea is new; come here when you want to find out whether you can turn it into marks. Completely free, no account needed to read.
What these questions ask of you
7 command words run through this set, and on Pearson Edexcel International GCSE Chemistry each one means something precise. Answering the wrong command is the commonest way a candidate who understands the lesson still loses the mark.
- Which (1 mark)
- one option chosen from the set given
- Give (1–2 marks)
- a short factual answer — the most common chemistry command
- Name (1 mark)
- the correct chemical name
- Describe (2–5 marks)
- developed, linked statements of what happens or what is observed Misread as: giving one bare observation where the tariff asked for a developed account
- Explain (2–4 marks)
- the reason, in terms of particles, bonding, energy or equilibrium Misread as: describing the observation without giving the chemistry that causes it
- Suggest (1–3 marks)
- a plausible answer applying taught chemistry to an unfamiliar substance
- Calculate (1–4 marks)
- a numerical answer with working, to the stated precision
Assessed on Paper 1 (4CH1/1C) and Paper 2 (4CH1/2C), against AO1, AO2, AO3.
Where these sit in the specification
Pearson Edexcel International GCSE Chemistry (4CH1) — statements 2.9 · 2.10 · 2.14. Incandio is aligned to this specification; it is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording.
The 12 questions
Answer them on paper, then open the lesson's exam practice to have them marked. The mark scheme, the accepted and rejected answers and the annotated model answer are in Incandio and are not printed here — an answer beside its question is not practice.
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A student pushed 100 cm³ of air backwards and forwards over heated copper using two gas syringes, until the volume stopped changing. She let the apparatus cool and then read the final volume as 79 cm³. The copper had turned from pink-brown to black.
(a)
(1)Give
Give the volume of gas that was removed from the sample.
A student pushed 100 cm³ of air backwards and forwards over heated copper using two gas syringes, until the volume stopped changing. She let the apparatus cool and then read the final volume as 79 cm³. The copper had turned from pink-brown to black.
............................ cm3
(b)
(2)Calculate
Calculate the percentage of oxygen in the air sample from these results.
A student pushed 100 cm³ of air backwards and forwards over heated copper using two gas syringes, until the volume stopped changing. She let the apparatus cool and then read the final volume as 79 cm³. The copper had turned from pink-brown to black.
percentage of oxygen = ............................ %
(c)
(3)Explain
Explain what the change in the colour of the copper shows about the reaction.
A student pushed 100 cm³ of air backwards and forwards over heated copper using two gas syringes, until the volume stopped changing. She let the apparatus cool and then read the final volume as 79 cm³. The copper had turned from pink-brown to black.
(d)
(3)Suggest
Suggest why the student pushed the gas over the copper repeatedly instead of once, and what she would have found had she stopped after one pass.
A student pushed 100 cm³ of air backwards and forwards over heated copper using two gas syringes, until the volume stopped changing. She let the apparatus cool and then read the final volume as 79 cm³. The copper had turned from pink-brown to black.
(Total for Question 1 = 9 marks)
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(1)Which
Which gas makes up about 78% of dry air by volume?
Gas A oxygen B nitrogen C argon D carbon dioxide (Total for Question 2 = 1 mark)
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(1)Give
Give the approximate percentage of oxygen in dry air by volume.
approximate percentage of oxygen = ............................ %
(Total for Question 3 = 1 mark)
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(1)Name
Name the noble gas present in dry air in the greatest amount.
(Total for Question 4 = 1 mark)
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(2)Describe
Describe how heated copper can be used to remove the oxygen from a sample of air.
(Total for Question 5 = 2 marks)
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(3)Explain
Explain why the copper used in this experiment must be in excess.
(Total for Question 6 = 3 marks)
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(2)Explain
Explain why the apparatus must be allowed to cool before the final volume is read.
(Total for Question 7 = 2 marks)
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(3)Suggest
Suggest why burning a candle in a sealed jar over water gives a poorer estimate of the percentage of oxygen than the copper method.
(Total for Question 8 = 3 marks)
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(4)Explain
Explain why the percentage of oxygen in the air stays close to 21% even though respiration and combustion remove it continuously.
(Total for Question 9 = 4 marks)
Have them marked, then defend the answer
Practice tells you the mark; teaching it back tells you whether you understand it. On Incandio a topic counts as mastered only once you have taught it and defended it.
- Mark these questions — 12 questions, marked on Incandio against the authored scheme, with the mistake you actually made named.
- Teach it — explain the Gases in the Air to Ember, an AI pupil who does not have it yet and asks the awkward question.
- Defend it — argue it against Joseph Priestley over three rounds, marked against descriptors you can read first.
Completely free. No subscriptions, no paywalls, no account needed to start.
Back to the lesson
- The Gases in the Air — Four gases, one of which is doing almost all the chemistry — and how to measure it without ever touching it.
- All of Incandio Chemistry · Incandio Exam Practice