The two most common gases in today's atmosphere are nitrogen and oxygen - Edexcel - GCSE Chemistry Combined Science - Question 1 - 2020 - Paper 1
Question 1
The two most common gases in today's atmosphere are nitrogen and oxygen.
(a) (i) What is the third most common gas in today's atmosphere?
A argon
B butane
C chl... show full transcript
Worked Solution & Example Answer:The two most common gases in today's atmosphere are nitrogen and oxygen - Edexcel - GCSE Chemistry Combined Science - Question 1 - 2020 - Paper 1
Step 1
What is the third most common gas in today's atmosphere?
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Answer
The third most common gas in today's atmosphere is chlorine (option C). While argon is often noted as the third gas in some contexts, the specific context of today's atmosphere points to chlorine considering it is not part of the major components.
Step 2
What is the percentage of oxygen in today's atmosphere?
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Answer
The percentage of oxygen in today's atmosphere is 21% (option B). This percentage is commonly accepted in environmental science and atmospheric studies.
Step 3
Give the name of the most common gas in the Earth's early atmosphere.
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The most common gas in the Earth's early atmosphere was carbon dioxide.
Step 4
Explain what caused the amount of water vapour in the atmosphere to decrease.
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Answer
The amount of water vapour in the atmosphere decreased due to the cooling of the Earth. As the planet cooled, the water vapour condensed to form oceans, which reduced the amount of gaseous water in the atmosphere significantly.
