Identifying the Products of Chemical Reactions (OCR Gateway GCSE Chemistry: Combined Science)

Exam Questions

13 mins9 questions
11 mark

Damp litmus paper is used to test for chlorine gas.

Which statement describes the correct result of the test for chlorine gas?

  • Damp blue litmus paper turns red then white.

  • Damp blue litmus paper turns white then red.

  • Damp red litmus paper turns blue then white.

  • Damp red litmus paper turns white then blue.

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21 mark

What is the test for chlorine gas?

  • Damp universal indicator paper turns red then white

  • Decolourises bromine water

  • Limewater turns milky

  • Relights a glowing splint

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11 mark

During the electrolysis of brine, chlorine gas forms at one electrode.

2Cl- (aq) rightwards arrowCl2 (g) + 2e-

Which test would be most appropriate to confirm that chlorine gas was produced?

  • Collect the gas and see if it extinguishes a glowing splint

  • Collect the gas and check if it is green

  • Collect the gas and see if it bleaches damp litmus paper

  • Collect the gas and check if it smells of swimming pools

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21 mark

Which is the correct method for testing for hydrogen gas?

  • Hold the tube containing the gas upright and place a lit splint at the end of the tube

  • Hold the tube containing the gas upright and place a glowing splint at the end of the tube

  • Hold the tube containing the gas angled down and place a lit splint at the end of the tube

  • Hold the tube containing the gas angled down and place a glowing splint at the end of the tube

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31 mark

Which is not true about the test for carbon dioxide gas?

  • The gas is bubbled through limewater solution

  • Limewater is calcium hydroxide solution

  • The solution will turn cloudy due to the formation of a white precipitate

  • The colour will fade after a few minutes

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41 mark

What is the correct observation when a glowing splint is held at the entrance of a tube of pure oxygen gas? 

  • A 'squeaky pop' sound can be heard

  • The glowing splint relights

  • The glowing splint keeps glowing

  • The glowing splint is immediately extinguished

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51 mark

The electrolysis of fresh water produces hydrogen gas and oxygen gas.

The electrolysis of salt water (brine) produces hydrogen gas and chlorine, and leaves a solution of sodium hydroxide.

Which test would not help to identify a sample as being fresh water or salt water?

  • A gas collected makes a 'squeaky pop' when a lit splint is held in it

  • A gas collected relights a glowing splint

  • A gas collected bleaches damp litmus paper

  • The pH of the solution increases

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61 mark

Which statement describes the test for chlorine gas?

  • A lighted splint makes a squeaky pop.

  • Limewater turns milky.

  • A glowing splint re-lights.

  • Damp litmus paper is bleached.

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