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9.2 Earth and atmospheric science

9.2 Earth and atmospheric science

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Question 22

A geochemist prepares two sealed chambers, Chamber A and Chamber B, containing simulated atmospheres. One chamber mimics the atmosphere of early Earth (approximately 4 billion years ago), while the other mimics Earth's modern atmosphere.

To identify the contents of each chamber, the geochemist performs two diagnostic tests on gas samples of equal volume:

  1. Turbidity Test: The gas is bubbled through a saturated calcium hydroxide solution (limewater). The time taken for the mixture to reach a turbidity of 50 NTU (cloudiness threshold) is recorded.
  2. Copper Oxidation Test: The gas is passed repeatedly over a heated copper spiral to react all oxygen into solid copper(II) oxide. The percentage decrease in the total gas volume is measured.

The experimental results are recorded in the table below:

TestChamber AChamber B
Time to reach 50 NTU4.2 seconds285.0 seconds
Percentage volume contraction0.2%20.8%

Explain, using the data in the table, which chamber contains the simulated gas mixture representing Earth's early atmosphere.

[2]
Markscheme

9.2 Earth and atmospheric science Questions

  1. GCSE
  2. /Chemistry
  3. /9.2 Earth and atmospheric science

97 exam-style questions on Edexcel GCSE Chemistry 9.2 Earth and atmospheric science, covering 9.2.1 The Earth's early atmosphere, 9.2.2 How the atmosphere evolved, 9.2.3 Chemical test for oxygen, and 9.2.4 The greenhouse effect and climate change. Each one has a worked solution and a mark scheme showing where the marks go.

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