Question 1

The student tests the gas produced by bubbling it through limewater. No change is seen in the limewater. Give one conclusion the student can make about the gas.

Accepted Answer

1. Recall the chemical test that uses limewater. What gas is it used to identify?
2. Recall the positive result for this test (limewater turns cloudy/milky).
3. The question states that "no change is seen".
4. What does this negative result tell you about the gas produced?

Question 2

What mistakes do candidates make on this AQA GCSE question?

Accepted Answer

✗ Stating what the gas *is* (e.g., "the gas is hydrogen"). While this is likely true for this reaction, the limewater test itself only proves the absence of CO₂, not the presence of another gas.

The student tests the gas produced by bubbling it through limewater. No change is seen in the limewater. Give one conclusion the student can make about the gas.

How to approach this question

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Common mistakes

Practice the full AQA GCSE Chemistry Foundation Tier Paper 2

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