Air Composition — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Air Composition MCQs with step-by-step solutions (5 questions). Part of Substances in Daily Use & Applied Chemistry. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Air Composition · medium · theory
The most abundant gas in the Earth's atmosphere is:
A. nitrogen ✓ Correct
B. argon
C. oxygen
D. carbon dioxide
Solution: Nitrogen makes up about 78% of the air by volume.
Q2 — Air Composition · medium · theory
The percentage of oxygen in the air is approximately:
A. 50%
B. 78%
C. 1%
D. 21% ✓ Correct
Solution: Oxygen makes up about 21% of the atmosphere.
Q3 — Air Composition · hard · theory
The approximate percentage of carbon dioxide in normal air is:
A. about 21%
B. about 10%
C. about 78%
D. about 0.04% ✓ Correct
Solution: CO₂ is a minor component, only about 0.03–0.04% of the air.
Q4 — Air Composition · hard · theory
The most abundant noble gas present in air is:
A. neon
B. krypton
C. helium
D. argon ✓ Correct
Solution: Argon makes up about 0.9% of the atmosphere — the most abundant noble gas in air.
Q5 — Air Composition · medium · theory
Which gas in the air is essential for the process of respiration and burning?
A. nitrogen
B. oxygen ✓ Correct
C. carbon dioxide
D. argon
Solution: Oxygen supports respiration and combustion.