📘 Chapter 4 – Air
💨 MCQ Questions (50) with Answers – Full Details in English
🧠 Multiple Choice Questions (MCQs) with Answers
1️⃣ The blanket of air that surrounds the Earth is called —
(a) Lithosphere
(b) Hydrosphere
(c) Atmosphere
(d) Biosphere
👉 Answer: (c) Atmosphere
2️⃣ The atmosphere extends up to about —
(a) 100 km
(b) 500 km
(c) 1,000 km
(d) 1,600 km
👉 Answer: (d) 1,600 km
3️⃣ The lowest layer of the atmosphere is —
(a) Stratosphere
(b) Troposphere
(c) Mesosphere
(d) Thermosphere
👉 Answer: (b) Troposphere
4️⃣ Weather phenomena occur in which layer?
(a) Stratosphere
(b) Troposphere
(c) Mesosphere
(d) Thermosphere
👉 Answer: (b) Troposphere
5️⃣ The layer that contains the ozone layer is —
(a) Stratosphere
(b) Mesosphere
(c) Thermosphere
(d) Troposphere
👉 Answer: (a) Stratosphere
6️⃣ The ozone layer protects us from —
(a) Infrared rays
(b) Ultraviolet rays
(c) X-rays
(d) Visible rays
👉 Answer: (b) Ultraviolet rays
7️⃣ The layer that helps in radio communication is —
(a) Ionosphere
(b) Stratosphere
(c) Mesosphere
(d) Troposphere
👉 Answer: (a) Ionosphere
8️⃣ The coldest layer of the atmosphere is —
(a) Mesosphere
(b) Stratosphere
(c) Thermosphere
(d) Troposphere
👉 Answer: (a) Mesosphere
9️⃣ The uppermost layer of the atmosphere is —
(a) Troposphere
(b) Stratosphere
(c) Exosphere
(d) Thermosphere
👉 Answer: (c) Exosphere
10️⃣ The main component of air is —
(a) Carbon dioxide
(b) Oxygen
(c) Nitrogen
(d) Hydrogen
👉 Answer: (c) Nitrogen
11️⃣ The percentage of nitrogen in the atmosphere is about —
(a) 21%
(b) 78%
(c) 0.03%
(d) 1%
👉 Answer: (b) 78%
12️⃣ The percentage of oxygen in the atmosphere is about —
(a) 21%
(b) 78%
(c) 1%
(d) 0.03%
👉 Answer: (a) 21%
13️⃣ Carbon dioxide makes up about —
(a) 0.03%
(b) 0.3%
(c) 3%
(d) 10%
👉 Answer: (a) 0.03%
14️⃣ Which gas is essential for respiration?
(a) Nitrogen
(b) Oxygen
(c) Carbon dioxide
(d) Ozone
👉 Answer: (b) Oxygen
15️⃣ Which gas is used by plants to prepare food?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Ozone
👉 Answer: (c) Carbon dioxide
16️⃣ The process by which plants make food is —
(a) Respiration
(b) Photosynthesis
(c) Transpiration
(d) Germination
👉 Answer: (b) Photosynthesis
17️⃣ The gas that traps heat and keeps the Earth warm is —
(a) Nitrogen
(b) Oxygen
(c) Carbon dioxide
(d) Ozone
👉 Answer: (c) Carbon dioxide
18️⃣ Which gas helps in burning?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Argon
👉 Answer: (a) Oxygen
19️⃣ The amount of water vapor in the air is called —
(a) Humidity
(b) Temperature
(c) Pressure
(d) Climate
👉 Answer: (a) Humidity
20️⃣ The pressure exerted by air is called —
(a) Wind
(b) Air pressure
(c) Humidity
(d) Temperature
👉 Answer: (b) Air pressure
21️⃣ The instrument used to measure air pressure is —
(a) Thermometer
(b) Barometer
(c) Anemometer
(d) Hygrometer
👉 Answer: (b) Barometer
22️⃣ Air moves from —
(a) High pressure to low pressure
(b) Low pressure to high pressure
(c) North to south
(d) East to west
👉 Answer: (a) High pressure to low pressure
23️⃣ The movement of air from high pressure to low pressure is called —
(a) Rain
(b) Wind
(c) Storm
(d) Cloud
👉 Answer: (b) Wind
24️⃣ The instrument used to measure wind speed is —
(a) Barometer
(b) Anemometer
(c) Thermometer
(d) Hygrometer
👉 Answer: (b) Anemometer
25️⃣ The hot winds blowing in northern India in summer are called —
(a) Monsoon
(b) Loo
(c) Cyclone
(d) Typhoon
👉 Answer: (b) Loo
26️⃣ The wind that blows regularly in one direction is called —
(a) Permanent wind
(b) Local wind
(c) Seasonal wind
(d) Cyclone
👉 Answer: (a) Permanent wind
27️⃣ Winds that change their direction with season are called —
(a) Monsoon winds
(b) Trade winds
(c) Westerlies
(d) Local winds
👉 Answer: (a) Monsoon winds
28️⃣ Which of the following is a local wind?
(a) Loo
(b) Trade wind
(c) Westerlies
(d) Monsoon
👉 Answer: (a) Loo
29️⃣ The instrument used to measure temperature is —
(a) Thermometer
(b) Barometer
(c) Rain gauge
(d) Anemometer
👉 Answer: (a) Thermometer
30️⃣ The average weather condition of a place over a long period is called —
(a) Climate
(b) Season
(c) Rainfall
(d) Temperature
👉 Answer: (a) Climate
31️⃣ The water cycle depends mainly on —
(a) Heat from the sun
(b) Moonlight
(c) Wind
(d) Air pressure
👉 Answer: (a) Heat from the sun
32️⃣ Which gas forms 0.9% of the atmosphere?
(a) Argon
(b) Oxygen
(c) Carbon dioxide
(d) Nitrogen
👉 Answer: (a) Argon
33️⃣ The average air pressure at sea level is —
(a) 760 mm
(b) 800 mm
(c) 700 mm
(d) 900 mm
👉 Answer: (a) 760 mm
34️⃣ Which layer of the atmosphere is ideal for flying airplanes?
(a) Stratosphere
(b) Troposphere
(c) Mesosphere
(d) Thermosphere
👉 Answer: (a) Stratosphere
35️⃣ The greenhouse effect is caused mainly by —
(a) Carbon dioxide
(b) Oxygen
(c) Nitrogen
(d) Ozone
👉 Answer: (a) Carbon dioxide
36️⃣ Excess of carbon dioxide in the atmosphere leads to —
(a) Global warming
(b) Acid rain
(c) Earthquake
(d) Flood
👉 Answer: (a) Global warming
37️⃣ The process of evaporation and condensation together form —
(a) Water cycle
(b) Rock cycle
(c) Oxygen cycle
(d) Nitrogen cycle
👉 Answer: (a) Water cycle
38️⃣ Which of the following gases is a greenhouse gas?
(a) Carbon dioxide
(b) Methane
(c) Water vapor
(d) All of these
👉 Answer: (d) All of these
39️⃣ The movement of air due to differences in temperature and pressure is called —
(a) Wind circulation
(b) Atmospheric circulation
(c) Ocean current
(d) Rotation
👉 Answer: (b) Atmospheric circulation
40️⃣ Air becomes lighter when —
(a) Heated
(b) Cooled
(c) Pressurized
(d) Compressed
👉 Answer: (a) Heated
41️⃣ The vertical movement of air is known as —
(a) Convection
(b) Conduction
(c) Radiation
(d) Reflection
👉 Answer: (a) Convection
42️⃣ Which of the following affects the distribution of temperature?
(a) Latitude
(b) Altitude
(c) Distance from sea
(d) All of these
👉 Answer: (d) All of these
43️⃣ The process of plants releasing water vapor is called —
(a) Transpiration
(b) Condensation
(c) Evaporation
(d) Precipitation
👉 Answer: (a) Transpiration
44️⃣ Rainfall is measured by an instrument called —
(a) Rain gauge
(b) Thermometer
(c) Barometer
(d) Anemometer
👉 Answer: (a) Rain gauge
45️⃣ Clouds are formed by —
(a) Condensation
(b) Evaporation
(c) Precipitation
(d) Melting
👉 Answer: (a) Condensation
46️⃣ The process by which water vapor changes into water is —
(a) Condensation
(b) Evaporation
(c) Precipitation
(d) Transpiration
👉 Answer: (a) Condensation
47️⃣ The process by which water changes into vapor is —
(a) Evaporation
(b) Condensation
(c) Precipitation
(d) Transpiration
👉 Answer: (a) Evaporation
48️⃣ When condensed water droplets become too heavy to remain in air, they fall as —
(a) Rain
(b) Snow
(c) Hail
(d) All of these
👉 Answer: (d) All of these
49️⃣ The movement of moisture from oceans to land and back is called —
(a) Water cycle
(b) Oxygen cycle
(c) Rock cycle
(d) Nitrogen cycle
👉 Answer: (a) Water cycle
50️⃣ The composition of air remains almost the same up to —
(a) 80 km
(b) 100 km
(c) 120 km
(d) 150 km
👉 Answer: (b) 100 km
🌤️ Quick Revision Summary
| 🌍 Topic | 🌬️ Key Facts |
|---|---|
| Main Gases | Nitrogen (78%), Oxygen (21%), Others (1%) |
| Layers of Atmosphere | Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere |
| Ozone Layer | Protects from UV rays (found in Stratosphere) |
| Wind Movement | High pressure → Low pressure |
| Instruments | Barometer (Pressure), Thermometer (Temperature), Anemometer (Wind), Rain Gauge (Rainfall) |
| Processes | Evaporation → Condensation → Precipitation → Water Cycle |
| Important Phenomena | Greenhouse Effect, Global Warming, Monsoon Winds |