Pearson Edexcel International GCSE in Chemistry · 4CH1 · Free · no account needed
Tests for Gases, and for Water — exam questions
12 original Incandio exam-style questions on Tests for Gases, and for Water, 27 marks, about 27 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 Tests for Gases, and for Water — 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
- Identify (1–2 marks)
- the correct substance or feature selected from what is given
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 2.44 · 2.49 · 2.50. 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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Table 1 — four gases collected from four reactions Gas Test carried out Result W lighted splint held at the mouth of the tube squeaky pop X bubbled through limewater limewater turned milky Y damp red litmus paper held in the gas paper turned blue Z damp blue litmus paper held in the gas paper bleached white (a)
(1)Identify
Identify gas W in Table 1.
Table 1 — four gases collected from four reactions Gas Test carried out Result W lighted splint held at the mouth of the tube squeaky pop X bubbled through limewater limewater turned milky Y damp red litmus paper held in the gas paper turned blue Z damp blue litmus paper held in the gas paper bleached white (b)
(2)Give
Give the names of gases X and Y in Table 1.
Table 1 — four gases collected from four reactions Gas Test carried out Result W lighted splint held at the mouth of the tube squeaky pop X bubbled through limewater limewater turned milky Y damp red litmus paper held in the gas paper turned blue Z damp blue litmus paper held in the gas paper bleached white (c)
(3)Explain
Explain how the results for gases Y and Z in Table 1 show that they are not the same gas.
Table 1 — four gases collected from four reactions Gas Test carried out Result W lighted splint held at the mouth of the tube squeaky pop X bubbled through limewater limewater turned milky Y damp red litmus paper held in the gas paper turned blue Z damp blue litmus paper held in the gas paper bleached white (d)
(3)Suggest
Suggest why a student who used a lighted splint on gas Z in Table 1 might have concluded, wrongly, that it was carbon dioxide.
Table 1 — four gases collected from four reactions Gas Test carried out Result W lighted splint held at the mouth of the tube squeaky pop X bubbled through limewater limewater turned milky Y damp red litmus paper held in the gas paper turned blue Z damp blue litmus paper held in the gas paper bleached white (Total for Question 1 = 9 marks)
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(1)Which
Which is the correct test for oxygen?
Test and result A a lighted splint gives a squeaky pop B a glowing splint relights C limewater turns milky D damp red litmus turns blue (Total for Question 2 = 1 mark)
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(1)Give
Give the result of bubbling carbon dioxide through limewater.
(Total for Question 3 = 1 mark)
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(1)Name
Name the white solid that turns blue when water is added to it.
(Total for Question 4 = 1 mark)
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(2)Describe
Describe the test for ammonia gas and the result that would be seen.
(Total for Question 5 = 2 marks)
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(3)Explain
Explain why the litmus paper used in the tests for ammonia and chlorine must be damp.
(Total for Question 6 = 3 marks)
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(2)Describe
Describe a physical test that would show whether a sample of water is pure.
(Total for Question 7 = 2 marks)
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(3)Suggest
A sample of seawater turns anhydrous copper(II) sulfate blue. Suggest why this does not show that the sample is pure water.
(Total for Question 8 = 3 marks)
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(5)Describe
Describe the tests that would distinguish between hydrogen, oxygen, carbon dioxide and chlorine, giving the result for each.
(Total for Question 9 = 5 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 Tests for Gases, and for Water 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.
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Back to the lesson
- Tests for Gases, and for Water — Five gases, five tests — and the difference between something being water and being pure water.
- All of Incandio Chemistry · Incandio Exam Practice