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The Earth’s early atmosphere was a mixture of gases - AQA - GCSE Chemistry - Question 5 - 2017 - Paper 1
Question 5
The Earth’s early atmosphere was a mixture of gases. One theory is that the Earth’s early atmosphere had the composition shown in Table 4. Gas Pe... show full transcript
Worked Solution & Example Answer:The Earth’s early atmosphere was a mixture of gases - AQA - GCSE Chemistry - Question 5 - 2017 - Paper 1
Step 1
Suggest one reason why this conclusion may not be correct.
Answer
One reason could be that not all gases required for amino acid formation were present in the Earth’s early atmosphere. The conditions of the experiments conducted by Miller and Urey may not accurately reflect the natural conditions on early Earth.
Step 2
Give three reasons why the percentage of carbon dioxide in the Earth’s atmosphere today is less than the percentage of carbon dioxide in the Earth’s early atmosphere.
Answer
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Carbon dioxide is used by plants and algae for photosynthesis, effectively reducing its concentration in the atmosphere.
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Carbon dioxide is absorbed and dissolved by oceans, where it becomes locked up in carbonates, further decreasing atmospheric levels.
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Significant amounts of carbon dioxide are stored in fossil fuels, which means less remains in the atmosphere.
Step 4
Step 5
Step 6
Explain why each stage is needed in the production of steel.
Answer
Stage 1: The introduction of oxygen reacts with carbon in the cast iron, decreasing the carbon content and converting it to steel, which is necessary for achieving desired properties.
Stage 2: Adding small amounts of other metals allows the steel to develop specific properties, ensuring it is not too brittle or soft, thus making it suitable for various applications.