Air: Composition, Properties, and Importance
8 minFull explanation, worked examples & memory tricks in the app
Kit Library / Science / Environmental Science
⚡ Topic Learning KitAir Basics
English 15 leveled MCQs Free
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Leveled MCQ practice
Try the smart MCQs from this kit
All 15 questions, laddered from warm-up to topper-level, each with its answer and the reasoning behind it.
Warm-up · 9 questions
Q1. Which gas makes up the largest portion of Earth's atmosphere?
Beginner
A
Nitrogen
B
Oxygen
C
Argon
D
Carbon dioxide
Show the answer
A · Nitrogen
Nitrogen constitutes about 78% of the atmosphere, making it the most abundant gas.
Q2. What is the approximate percentage of oxygen in the air?
Beginner
A
21%
B
50%
C
0.04%
D
78%
Show the answer
A · 21%
Oxygen makes up about 21% of the atmosphere, essential for respiration.
Q3. Which gas is used by plants during photosynthesis?
Beginner
A
Carbon dioxide
B
Hydrogen
C
Nitrogen
D
Oxygen
Show the answer
A · Carbon dioxide
Plants take in carbon dioxide from the air for photosynthesis.
Q4. What is the main cause of air pollution?
Beginner
A
Plant transpiration
B
Ocean currents
C
Volcanic eruptions
D
Burning of fossil fuels
Show the answer
D · Burning of fossil fuels
Burning fossil fuels releases pollutants like carbon monoxide, sulfur dioxide, and particulate matter.
Q5. What is the term for the weight of air pressing down on Earth's surface?
Beginner
A
Wind speed
B
Humidity
C
Temperature
D
Air pressure
Show the answer
D · Air pressure
Air pressure is the force exerted by the weight of air molecules.
Q6. What is the process by which plants release water vapor into the air?
Beginner
A
Respiration
B
Photosynthesis
C
Condensation
D
Transpiration
Show the answer
D · Transpiration
Transpiration is the loss of water vapor from plant leaves, contributing to humidity.
Q7. Which atmospheric layer is closest to Earth's surface?
Beginner
A
Stratosphere
B
Mesosphere
C
Troposphere
D
Thermosphere
Show the answer
C · Troposphere
The troposphere is the lowest layer where weather occurs.
Q8. Air is a pure substance.
Beginner
A
True
B
False
Show the answer
B · False
Air is a mixture of gases, not a pure substance.
Q9. The percentage of carbon dioxide in the atmosphere is higher than that of oxygen.
Beginner
A
True
B
False
Show the answer
B · False
Carbon dioxide is about 0.04%, while oxygen is about 21%.
Building up · 6 questions
Q10. Which of the following is a noble gas found in trace amounts in air?
Intermediate
A
Argon
B
Oxygen
C
Carbon dioxide
D
Nitrogen
Show the answer
A · Argon
Argon is a noble gas present in about 0.93% of the atmosphere.
Q11. What is the primary source of energy that drives atmospheric circulation?
Intermediate
A
The Moon
B
The Sun
C
Wind
D
Geothermal heat
Show the answer
B · The Sun
Solar energy heats the Earth unevenly, causing air movement and weather patterns.
Q12. Which layer of the atmosphere contains the ozone layer?
Intermediate
A
Stratosphere
B
Thermosphere
C
Mesosphere
D
Troposphere
Show the answer
A · Stratosphere
The ozone layer is located in the stratosphere, protecting life from UV radiation.
Q13. Which gas is responsible for the greenhouse effect?
Intermediate
A
Argon
B
Oxygen
C
Nitrogen
D
Carbon dioxide
Show the answer
D · Carbon dioxide
Carbon dioxide traps heat in the atmosphere, contributing to global warming.
Q14. Which of the following is a primary air pollutant?
Intermediate
A
Sulfuric acid
B
Nitric acid
C
Carbon monoxide
D
Ozone
Show the answer
C · Carbon monoxide
Carbon monoxide is emitted directly from sources like vehicles and is a primary pollutant.
Q15. What is the main component of smog?
Intermediate
A
Carbon dioxide and helium
B
Nitrogen and oxygen
C
Water vapor and argon
D
Ozone and particulate matter
Show the answer
D · Ozone and particulate matter
Smog is a mixture of pollutants, primarily ground-level ozone and fine particles.
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