8.4 Tests for gases
5 exam questions worth 8 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which test identifies oxygen?
Choose one answer.
Correct Not quite: the answer is A glowing splint relights
Mark scheme
B
Model answer
B: oxygen relights a glowing splint.
Describe the test for hydrogen and give the result.
Mark scheme
- lit splint at the mouth of the tube (1)
- squeaky pop (1)
Model answer
Hold a lit splint at the mouth of the test tube; hydrogen burns with a squeaky pop.
Describe the test for carbon dioxide and give the result.
Mark scheme
- bubble through limewater (1)
- turns milky / cloudy (1)
Model answer
Bubble the gas through limewater; it turns milky.
Explain why the litmus paper used to test for chlorine must be damp.
Mark scheme
- chlorine must dissolve in water (on the paper) to bleach it (1)
Model answer
Chlorine has to dissolve in water on the paper to form the acidic, bleaching solution.
A student adds a metal to an acid and collects the gas. A lit splint makes a squeaky pop.
Name the gas and write a word equation for the reaction that causes the pop.
Mark scheme
- hydrogen (1)
- hydrogen + oxygen → water (1)
Model answer
The gas is hydrogen. hydrogen + oxygen → water.
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