Composition of Air — Homi Bhabha Class 6 Chemistry MCQs with Solutions
Free Homi Bhabha Class 6 Chemistry Composition of Air MCQs with step-by-step solutions (10 questions). Part of Air and Atmosphere. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Composition of Air · easy · theory
Which gas is present in the largest amount in air?
A. Water vapour
B. Carbon dioxide
C. Oxygen
D. Nitrogen ✓ Correct
Solution: Nitrogen makes up about 78% of air, far more than any other gas.
Q2 — Composition of Air · easy · theory
About one-fifth (nearly 21%) of the air is made up of which gas?
A. Hydrogen
B. Oxygen ✓ Correct
C. Carbon dioxide
D. Nitrogen
Solution: Oxygen makes up about 21% of air, which is roughly one-fifth of it.
Q3 — Composition of Air · easy · theory
Air is best described as …
A. A type of liquid
B. A mixture of several gases ✓ Correct
C. A single pure gas
D. A kind of metal
Solution: Air is a mixture of many gases such as nitrogen, oxygen and carbon dioxide, not a single pure gas.
Q4 — Composition of Air · easy · theory
Roughly how much of the air is nitrogen?
A. About 21%
B. About 50%
C. About 3%
D. About 78% ✓ Correct
Solution: Nitrogen forms about 78% of air, making it the most common gas in the air.
Q5 — Composition of Air · medium · theory
Which gas is present in air in only a very small amount, about 0.03%?
A. Argon
B. Oxygen
C. Carbon dioxide ✓ Correct
D. Nitrogen
Solution: Carbon dioxide is only about 0.03% of air, a very small amount compared with nitrogen and oxygen.
Q6 — Composition of Air · medium · theory
Which of these is NOT a normal part of clean air?
A. Smoke ✓ Correct
B. Nitrogen
C. Oxygen
D. Carbon dioxide
Solution: Clean air has nitrogen, oxygen and a little carbon dioxide; smoke is a pollutant and is not part of clean air.
Q7 — Composition of Air · medium · numerical
Air is about 21% oxygen. In 100 litres of air, about how many litres are oxygen?
A. 78 litres
B. 100 litres
C. 21 litres ✓ Correct
D. 1 litre
Solution: 21% of 100 litres = 21 litres, so about 21 litres of the air is oxygen.
Q8 — Composition of Air · medium · theory
The amount of which gas in air keeps changing from place to place and day to day?
A. Nitrogen
B. Water vapour ✓ Correct
C. Argon
D. Oxygen
Solution: The amount of water vapour in air is not fixed; it changes with the weather and the place.
Q9 — Composition of Air · hard · theory
Nitrogen and oxygen together make up about what part of the air?
A. About 3%
B. About 21%
C. About half
D. About 99% ✓ Correct
Solution: Nitrogen (about 78%) and oxygen (about 21%) together make up about 99% of air.
Q10 — Composition of Air · hard · theory
One reason we say air is a mixture and not a single pure gas is that …
A. It is made only in factories
B. It cannot be separated at all
C. It has just one gas in it
D. It can be separated into different gases like oxygen and nitrogen ✓ Correct
Solution: Air can be separated into its different gases, which shows it is a mixture of several gases and not one pure gas.