Importance of Gases — Homi Bhabha Class 6 Chemistry MCQs with Solutions
Free Homi Bhabha Class 6 Chemistry Importance of Gases 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 — Importance of Gases · easy · theory
Which gas in the air do humans and animals need for breathing?
A. Nitrogen
B. Carbon dioxide
C. Oxygen ✓ Correct
D. Water vapour
Solution: Living things use oxygen from the air to breathe and stay alive.
Q2 — Importance of Gases · easy · theory
Which gas do green plants use from the air to make their food?
A. Carbon dioxide ✓ Correct
B. Oxygen
C. Nitrogen
D. Hydrogen
Solution: Green plants take in carbon dioxide from the air and use it, with sunlight, to make their food.
Q3 — Importance of Gases · easy · theory
Which gas helps things burn?
A. Oxygen ✓ Correct
B. Nitrogen
C. Water vapour
D. Carbon dioxide
Solution: Oxygen supports burning; a fire cannot keep burning without oxygen.
Q4 — Importance of Gases · easy · theory
Which gas is often used in fire extinguishers to put out fires?
A. Oxygen
B. Carbon dioxide ✓ Correct
C. Hydrogen
D. Nitrogen
Solution: Carbon dioxide does not support burning and cuts off the oxygen, so it is used to put out fires.
Q5 — Importance of Gases · medium · theory
When we breathe out, which gas do we give out more of?
A. Carbon dioxide ✓ Correct
B. Nitrogen
C. Hydrogen
D. Oxygen
Solution: Our body uses up oxygen and gives out more carbon dioxide when we breathe out.
Q6 — Importance of Gases · medium · theory
Packets of chips are often filled with nitrogen gas because nitrogen …
A. Dissolves the oil in the chips
B. Makes the chips tasty
C. Is unreactive and keeps the food fresh ✓ Correct
D. Helps the chips burn
Solution: Nitrogen does not react easily, so it keeps the chips fresh and stops them from going stale.
Q7 — Importance of Gases · medium · theory
The fizz (bubbles) in cold drinks and soda is due to which gas?
A. Oxygen
B. Nitrogen
C. Water vapour
D. Carbon dioxide ✓ Correct
Solution: Cold drinks have carbon dioxide dissolved in them, which comes out as bubbles and gives the fizz.
Q8 — Importance of Gases · medium · theory
During the day, green plants mainly …
A. Take in carbon dioxide and give out oxygen ✓ Correct
B. Take in nitrogen and give out oxygen
C. Take in and give out only water
D. Take in oxygen and give out carbon dioxide
Solution: While making food in daylight, plants take in carbon dioxide and give out oxygen, which we need to breathe.
Q9 — Importance of Gases · hard · theory
Air does not burn up everything very quickly even though it contains oxygen. This is mainly because nitrogen …
A. Adds more oxygen to the fire
B. Burns even faster than oxygen
C. Cools the Sun
D. Does not support burning and slows it down ✓ Correct
Solution: Nitrogen does not support burning, so it dilutes the oxygen in air and keeps things from burning too fast.
Q10 — Importance of Gases · hard · theory
To test whether a gas is carbon dioxide, we pass it through lime water. If it is carbon dioxide, the lime water turns …
A. Deep blue
B. Milky (cloudy white) ✓ Correct
C. Grass green
D. Bright red
Solution: Carbon dioxide turns clear lime water milky (cloudy white), which is the common test for this gas.