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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. **Table 4** | Gas ... 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
Amino acids are at the basis of all life processes. Suggest one reason why this conclusion may not be correct.
Answer
One reason this conclusion may not be correct is that the conditions of the reaction may not have been representative of those on early Earth. No one knows what specific conditions were present that could lead to the formation of amino acids.
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
- Carbon dioxide is used by plants and algae for photosynthesis, reducing its concentration.
- Carbon dioxide is absorbed and dissolved by oceans, locking it away and decreasing atmospheric levels.
- Carbon dioxide is stored in locked-up fossil fuels, further reducing the amount present in the atmosphere.
Step 4
Step 5
Step 6
Explain why each stage is needed in the production of steel.
Answer
Stage 1: Oxygen reacts with carbon in cast iron, which decreases the carbon content and helps in removing impurities, as high carbon content can make steel brittle.
Stage 2: Adding small amounts of other metals allows for the creation of an alloy that enhances the properties of steel, ensuring that it is neither too soft nor too brittle.