Complete the sentence by putting a cross (X) in the box next to your answer - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Question 2
Complete the sentence by putting a cross (X) in the box next to your answer.
The Earth’s earliest atmosphere is thought to have been formed by
A animals breathing... show full transcript
Worked Solution & Example Answer:Complete the sentence by putting a cross (X) in the box next to your answer - Edexcel - GCSE Chemistry - Question 2 - 2015 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The Earth’s earliest atmosphere is thought to have been formed by D gases from volcanoes. This is because volcanic gases were the primary source of the early atmosphere.
Step 2
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The percentage of carbon dioxide in the Earth’s atmosphere today is C 21%. This reflects the balance of gases necessary for supporting life.
Step 3
Write the formula of a molecule of carbon dioxide.
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Answer
The formula of a molecule of carbon dioxide is CO₂. This indicates that each molecule consists of one carbon atom bonded to two oxygen atoms.
Step 4
Explain what has caused the amount of carbon dioxide in the atmosphere to decrease.
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Answer
The percentage of carbon dioxide in the atmosphere has decreased due to various factors, primarily the rise of photosynthetic organisms. Through photosynthesis, these organisms consume carbon dioxide and release oxygen, leading to a significant reduction in atmospheric CO₂ over geological time.
Step 5
State one human activity that increases the amount of carbon dioxide in the atmosphere today.
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Answer
One human activity that increases the amount of carbon dioxide in the atmosphere today is burning fossil fuels. This process releases large quantities of CO₂ into the atmosphere, contributing to climate change.
