1. The atmosphere is held around the Earth due to____________.
A) Earth’s rotation
B) Earth’s gravity
C) Solar radiation
D) Centrifugal force
Answer: B
Explanation: The gravitational pull of Earth holds the atmospheric gases around it.
2. Which gas is most abundant in the Earth’s atmosphere?
A) Oxygen
B) Carbon dioxide
C) Nitrogen
D) Argon
Answer: C
Explanation: Nitrogen forms ~78% of the atmosphere.
3. Oxygen constitutes about what percentage of the atmosphere?
A) 15%
B) 21%
C) 25%
D) 30%
Answer: B
Explanation: Oxygen makes up ~20.9% of the atmosphere.
4. The layer of the atmosphere closest to the Earth’s surface is____________.
A) Stratosphere
B) Mesosphere
C) Troposphere
D) Thermosphere
Answer: C
Explanation: Troposphere extends up to ~8–18 km from Earth’s surface and contains weather systems.
5. The upper boundary of the troposphere is called____________.
A) Tropopause
B) Stratopause
C) Mesopause
D) Thermopause
Answer: A
Explanation: Tropopause separates troposphere and stratosphere.
6. Which atmospheric layer contains the ozone layer?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: B
Explanation: Ozone concentration is highest between 15–35 km in the stratosphere.
7. The average height of the troposphere at the equator is about____________.
A) 8 km
B) 12 km
C) 16–18 km
D) 20 km
Answer: C
Explanation: The troposphere is thickest at the equator due to convectional uplift.
8. Which gas absorbs most of the harmful ultraviolet radiation?
A) Oxygen
B) Ozone
C) Nitrogen
D) Argon
Answer: B
Explanation: Ozone in the stratosphere absorbs UV-B and UV-C radiation.
9. Which atmospheric layer helps in radio communication by reflecting radio waves?
A) Troposphere
B) Stratosphere
C) Ionosphere
D) Exosphere
Answer: C
Explanation: Ionosphere (part of thermosphere) reflects radio waves due to charged particles.
10. The coldest part of the atmosphere is____________.
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: C
Explanation: Temperature falls up to −90°C in the mesosphere.
11. The hottest part of the atmosphere is____________.
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: D
Explanation: High energy solar radiation heats the thermosphere, raising temperatures to 1000°C or more.
12. Which gas is responsible for the greenhouse effect most significantly?
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Argon
Answer: C
Explanation: CO₂ traps infrared radiation, contributing to global warming.
13. The percentage of carbon dioxide in the atmosphere is about____________.
A) 0.03%
B) 0.1%
C) 0.3%
D) 1%
Answer: A
Explanation: Atmospheric CO₂ concentration is about 0.03–0.04%.
14. The exosphere mainly contains____________.
A) Oxygen and nitrogen
B) Hydrogen and helium
C) Ozone
D) Carbon dioxide
Answer: B
Explanation: The exosphere is the outermost layer with light gases like hydrogen and helium.
15. Which instrument is used to measure atmospheric pressure?
A) Thermometer
B) Anemometer
C) Barometer
D) Hygrometer
Answer: C
Explanation: Barometer measures atmospheric pressure, usually in millibars (mb).
16. One standard atmosphere pressure is equal to____________.
A) 1013.25 mb
B) 760 mm Hg
C) 29.92 inches of mercury
D) All of these
Answer: D
Explanation: Standard atmospheric pressure can be expressed in different units.
17. Which layer of atmosphere protects us from meteors?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Exosphere
Answer: C
Explanation: Meteors burn up in the mesosphere due to friction with air molecules.
18. The ionosphere is important for____________.
A) Rainfall
B) Ozone formation
C) Radio communication
D) Earthquake prediction
Answer: C
Explanation: Charged particles in the ionosphere reflect radio signals.
19. Which gas is essential for photosynthesis?
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Argon
Answer: C
Explanation: Plants use CO₂ to produce food during photosynthesis.
20. The composition of the atmosphere up to 80 km is called____________.
A) Heterosphere
B) Homosphere
C) Ionosphere
D) Exospher
Answer: B
Explanation: Homosphere is the well-mixed part of atmosphere up to 80 km.
21. Above 80 km, gases are stratified by molecular weight. This region is called____________.
A) Exosphere
B) Mesosphere
C) Heterosphere
D) Troposphere
Answer: C
Explanation: In the heterosphere, lighter gases are found at higher altitudes.
22. Which layer is known as the “weather-making” layer?
A) Stratosphere
B) Troposphere
C) Mesosphere
D) Thermosphere
Answer: B
Explanation: All weather phenomena like clouds, rainfall, storms occur in the troposphere.
23. Which of the following is NOT a greenhouse gas?
A) Water vapor
B) Carbon dioxide
C) Methane
D) Oxygen
Answer: D
Explanation: Oxygen does not absorb infrared radiation; it is not a greenhouse gas.
24. Which atmospheric gas has the highest capacity to absorb long-wave radiation per molecule?
A) CO₂
B) CH₄ (Methane)
C) N₂O (Nitrous oxide)
D) CFCs
Answer: D
Explanation: CFCs have the highest global warming potential among greenhouse gases.
25. The ozone hole is found over____________.
A) North America
B) Antarctica
C) Sahara Desert
D) Himalayas
Answer: B
Explanation: Ozone depletion is maximum over Antarctica due to polar stratospheric clouds.
26. The process of heating the atmosphere by short-wave solar radiation and long-wave terrestrial radiation is called____________.
A) Conduction
B) Convection
C) Radiation balance
D) Greenhouse effect
Answer: D
Explanation: The greenhouse effect occurs when gases trap heat radiated from Earth.
27. The tropopause is higher at the____________.
A) Poles
B) Mid-latitudes
C) Equator
D) Oceans
Answer: C
Explanation: At the equator, it rises up to ~18 km due to strong convection currents.
28. The atmosphere is divided into layers on the basis of____________.
A) Chemical composition
B) Temperature
C) Pressure
D) Density
Answer: B
Explanation: Atmospheric layers are distinguished by temperature variations with altitude.
29. The average lapse rate in the troposphere is____________.
A) 3.5°C per km
B) 5°C per km
C) 6.5°C per km
D) 10°C per km
Answer: C
Explanation: Temperature decreases by ~6.5°C per km in the troposphere.
30. The upper boundary of the stratosphere is called____________.
A) Stratopause
B) Tropopause
C) Mesopause
D) Exopause
Answer: A
Explanation: Stratopause marks the transition between stratosphere and mesosphere.
31. Which gas absorbs outgoing terrestrial radiation most effectively?
A) Oxygen
B) Ozone
C) Carbon dioxide
D) Argon
Answer: C
Explanation: CO₂ strongly absorbs infrared radiation, contributing to the greenhouse effect.
32. Which is the least abundant gas in the atmosphere among the following?
A) Argon
B) Carbon dioxide
C) Neon
D) Krypton
Answer: D
Explanation: Krypton is present only in trace amounts.
33. Jet streams occur in which layer of the atmosphere?
A) Troposphere
B) Stratosphere (upper troposphere-lower stratosphere boundary)
C) Mesosphere
D) Thermosphere
Answer: B
Explanation: Jet streams blow at ~9–14 km altitude, near tropopause.
34. Which element of weather is measured by an anemometer?
A) Temperature
B) Humidity
C) Wind speed
D) Atmospheric pressure
Answer: C
Explanation: Anemometer measures wind velocity.
35. The instrument used to measure humidity is____________.
A) Thermometer
B) Barometer
C) Hygrometer
D) Pyranometer
Answer: C
Explanation: Hygrometer measures the moisture content of air.
36. The instrument used to measure solar radiation is____________.
A) Pyranometer
B) Thermometer
C) Barometer
D) Anemometer
Answer: A
Explanation: Pyranometer measures solar radiation intensity.
37. The total incoming solar radiation received at the Earth’s surface is called____________.
A) Insolation
B) Albedo
C) Radiative forcing
D) Solar constant
Answer: A
Explanation: Insolation refers to the solar energy received per unit area.
38. The percentage of insolation reflected back to space by Earth’s surface is called____________.
A) Radiation budget
B) Greenhouse effect
C) Albedo
D) Heat balance
Answer: C
Explanation: Albedo is the reflectivity of Earth’s surface.
39. The average albedo of Earth is about____________.
A) 10%
B) 20%
C) 30%
D) 50%
Answer: C
Explanation: About one-third of insolation is reflected back into space.
40. The solar constant is approximately____________.
A) 1.36 W/m²
B) 136 W/m²
C) 1360 W/m²
D) 13,600 W/m²
Answer: C
Explanation: Solar constant = 1361 W/m², energy received outside Earth’s atmosphere.
41. The term “weather” refers to atmospheric conditions over____________.
A) A long period
B) A short period
C) Entire Earth
D) Millions of years
Answer: B
Explanation: Weather means short-term atmospheric conditions.
42. The term “climate” refers to atmospheric conditions over____________.
A) Days
B) Weeks
C) 30 years or more
D) Hours
Answer: C
Explanation: Climate is long-term average of weather conditions.
43. The process of heat transfer by direct contact is called____________.
A) Radiation
B) Convection
C) Conduction
D) Advection
Answer: C
Explanation: Conduction transfers heat between molecules in contact.
44. The horizontal movement of air is known as____________.
A) Conduction
B) Convection
C) Advection
D) Radiation
Answer: C
Explanation: Advection is horizontal transfer of heat by air movement.
45. The vertical movement of air due to heating is called____________.
A) Conduction
B) Convection
C) Advection
D) Radiation
Answer: B
Explanation: Convection is upward movement of warm air and sinking of cold air.
46. Which factor decreases with increase in altitude?
A) Temperature
B) Pressure
C) Density
D) All of these
Answer: D
Explanation: Temperature, pressure, and density generally decrease with altitude.
47. Which gas is lighter and rises to the top in the exosphere?
A) Oxygen
B) Nitrogen
C) Hydrogen
D) Carbon dioxide
Answer: C
Explanation: Hydrogen is the lightest gas and is found in the outermost layer.
48. The aurora borealis (northern lights) occur in which layer?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: D
Explanation: Aurora occurs due to interaction of charged particles with Earth’s magnetic field in the thermosphere.
49. Which atmospheric layer is also called the “ionized layer”?
A) Troposphere
B) Ionosphere
C) Stratosphere
D) Mesosphere
Answer: B
Explanation: Ionosphere is filled with ions and free electrons, enabling radio communication.
50. Which layer marks the boundary between atmosphere and outer space?
A) Tropopause
B) Stratopause
C) Exosphere
D) Mesopause
Answer: C
Explanation: Exosphere (~600 km and above) merges gradually into outer space.
51. Which layer of the atmosphere is directly responsible for weather phenomena?
A) Stratosphere
B) Troposphere
C) Mesosphere
D) Thermosphere
Answer: B
Explanation: Weather like clouds, rainfall, winds, and storms all occur in the troposphere.
52. The stratosphere is preferred by jet aircrafts because____________.
A) It has high pressure
B) It has calm and stable conditions
C) It contains ozone
D) It is nearest to Earth
Answer: B
Explanation: Lack of turbulence in the stratosphere ensures smooth flying.
53. Which gas, though present in small amounts, is crucial for weather processes?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Water vapor
Answer: D
Explanation: Water vapor controls humidity, cloud formation, and rainfall.
54. The lapse rate in the troposphere is negative because____________.
A) Temperature increases with height
B) Temperature decreases with height
C) Pressure increases with height
D) Ozone absorbs UV rays
Answer: B
Explanation: In the troposphere, temperature drops ~6.5°C per km.
55. In the stratosphere, temperature increases with altitude because____________.
A) Ozone absorbs ultraviolet radiation
B) CO₂ absorbs heat
C) Water vapor condenses
D) Air pressure is high
Answer: A
Explanation: Ozone converts UV radiation into heat, raising stratospheric temperature.
56. The mesosphere is colder because____________.
A) It has ozone
B) It lacks water vapor and CO₂
C) It has high pressure
D) Solar energy is trapped
Answer: B
Explanation: These greenhouse gases are absent, causing rapid cooling.
57. Which phenomenon proves that the outer core of Earth is liquid, indirectly linked to atmosphere studies?
A) P-wave shadow zone
B) S-wave disappearance
C) Jet streams
D) Lapse rate
Answer: B
Explanation: S-waves don’t travel through liquid outer core; seismic studies help atmospheric sciences.
58. Which atmospheric layer extends roughly between 80 km and 480 km?
A) Troposphere
B) Stratosphere
C) Ionosphere
D) Exosphere
Answer: C
Explanation: Ionosphere lies within the thermosphere, 80–480 km altitude.
59. Which gas is absent in the stratosphere but abundant in the troposphere?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Water vapor
Answer: D
Explanation: Stratosphere is almost dry, while troposphere contains nearly all atmospheric water vapor.
60. The height of the mesosphere above Earth’s surface is about____________.
A) 0–12 km
B) 12–50 km
C) 50–80 km
D) 80–600 km
Answer: C
Explanation: Mesosphere extends from ~50 km to 80 km altitude.
61. The temperature in the thermosphere rises because____________.
A) Clouds trap heat
B) Ozone absorbs UV
C) Atoms absorb high-energy solar radiation
D) Reflection of sunlight
Answer: C
Explanation: Oxygen and nitrogen atoms absorb X-rays and UV radiation.
62. Which process removes carbon dioxide from the atmosphere?
A) Respiration
B) Combustion
C) Photosynthesis
D) Volcanism
Answer: C
Explanation: Plants absorb CO₂ during photosynthesis.
63. The pressure decreases with height because____________.
A) Gravity weakens
B) Gases escape
C) Density of air decreases
D) Temperature falls
Answer: C
Explanation: Fewer air molecules are present at higher altitudes.
64. What is the approximate percentage of Argon in the atmosphere?
A) 1%
B) 2%
C) 5%
D) 10%
Answer: A
Explanation: Argon is about 0.93% of the atmosphere.
65. Which atmospheric layer contains meteors that burn up?
A) Troposphere
B) Stratosphere
C) Mesosphere
D) Thermosphere
Answer: C
Explanation: Meteors burn due to friction in the mesosphere.
66. Which gas forms acid rain when combined with water vapor?
A) Oxygen
B) Nitrogen oxides and sulfur dioxide
C) Carbon dioxide
D) Ozone
Answer: B
Explanation: SO₂ and NOₓ react with water to form sulfuric and nitric acid.
67. The greenhouse gas with the highest global warming potential is____________.
A) Carbon dioxide
B) Methane
C) Nitrous oxide
D) CFCs
Answer: D
Explanation: CFCs trap thousands of times more heat per molecule than CO₂.
68. Which part of the atmosphere has auroras (northern and southern lights)?
A) Mesosphere
B) Troposphere
C) Thermosphere
D) Stratosphere
Answer: C
Explanation: Auroras occur due to charged particles in the thermosphere.
69. Atmospheric pressure is highest at____________.
A) Sea level
B) 1 km altitude
C) 5 km altitude
D) 10 km altitude
Answer: A
Explanation: Air pressure decreases with height, maximum at sea level.
70. Which element of weather is measured by a rain gauge?
A) Temperature
B) Wind
C) Humidity
D) Rainfall
Answer: D
Explanation: A rain gauge measures precipitation.
71. Winds blowing from sea to land are called____________.
A) Land breeze
B) Sea breeze
C) Monsoon
D) Trade winds
Answer: B
Explanation: Sea breeze occurs during daytime when land heats faster than sea.
72. Winds blowing from land to sea at night are called____________.
A) Sea breeze
B) Land breeze
C) Monsoon winds
D) Cyclonic winds
Answer: B
Explanation: At night, land cools faster, creating land-to-sea breeze.
73. Which gas in the atmosphere is essential for respiration?
A) Nitrogen
B) Oxygen
C) Carbon dioxide
D) Ozone
Answer: B
Explanation: Oxygen is vital for respiration in living beings.
74. Which instrument is used to measure wind direction?
A) Anemometer
B) Wind vane
C) Barometer
D) Hygrometer
Answer: B
Explanation: A wind vane indicates the direction of the wind.
75. The ozone layer is found between____________.
A) 5–10 km
B) 10–15 km
C) 15–35 km
D) 40–60 km
Answer: C
Explanation: Ozone concentration peaks in the stratosphere between 15–35 km altitude.
76. The layer that separates the mesosphere and thermosphere is called____________.
A) Tropopause
B) Stratopause
C) Mesopause
D) Exopause
Answer: C
Explanation: Mesopause lies at ~80 km, the coldest part of the atmosphere.
77. Which gas in the atmosphere is called “laughing gas”?
A) Carbon dioxide
B) Nitrous oxide (N₂O)
C) Methane
D) Ozone
Answer: B
Explanation: N₂O is known as laughing gas and is a greenhouse gas.
78. Which layer is also called the “blanket of silence” because sound cannot travel in it?
A) Troposphere
B) Stratosphere
C) Thermosphere
D) Mesosphere
Answer: C
Explanation: Air is very thin in thermosphere, so sound cannot propagate.
79. Atmospheric pressure is measured in____________.
A) Joules
B) Newtons
C) Pascals or millibars
D) Decibels
Answer: C
Explanation: Pressure units: 1 mb = 100 Pa.
80. The ozone layer is destroyed by____________.
A) Nitrogen
B) CFCs (Chlorofluorocarbons)
C) Carbon dioxide
D) Argon
Answer: B
Explanation: CFCs release chlorine atoms that break down ozone molecules.
81. The main cause of acid rain is____________.
A) CO₂
B) SO₂ and NOₓ
C) O₃
D) CH₄
Answer: B
Explanation: Sulfur dioxide and nitrogen oxides combine with water to form acid rain.
82. In the troposphere, most heat is transferred by____________.
A) Radiation
B) Convection
C) Conduction
D) Reflection
Answer: B
Explanation: Rising and sinking air currents (convection) transfer heat in the troposphere.
83. The atmospheric pressure at sea level is about____________.
A) 760 mm of Hg
B) 500 mm of Hg
C) 100 mm of Hg
D) 50 mm of Hg
Answer: A
Explanation: Sea-level standard pressure = 760 mm Hg (1013 mb).
84. Which instrument is used to measure sunshine duration?
A) Pyrheliometer
B) Campbell–Stokes recorder
C) Anemometer
D) Barograph
Answer: B
Explanation: It uses a glass sphere to record sunshine hours on paper.
85. The exosphere starts at about____________.
A) 20 km
B) 80 km
C) 200 km
D) 600 km
Answer: D
Explanation: Exosphere begins around 600 km and merges with outer space.
86. Which phenomenon is due to refraction of sunlight in the atmosphere?
A) Rainbow
B) Twilight
C) Aurora
D) Mirage
Answer: B
Explanation: Twilight (before sunrise and after sunset) is due to scattering and refraction of light.
87. The aurora australis is seen in____________.
A) Northern Hemisphere
B) Southern Hemisphere
C) Both hemispheres
D) Equator
Answer: B
Explanation: Aurora Australis occurs in the south polar region.
88. The equatorial calm zone with little wind is called____________.
A) Horse latitude
B) Doldrums
C) Westerlies
D) Polar front
Answer: B
Explanation: Doldrums are calm equatorial regions near ITCZ (0°–5°).
89. The subtropical calm belts at ~30° latitudes are called____________.
A) Doldrums
B) Horse latitudes
C) Westerlies
D) Polar easterlies
Answer: B
Explanation: Horse latitudes are calm high-pressure zones around 30° N & S.
90. The trade winds blow from____________.
A) Poles to equator
B) Subtropical highs to equatorial lows
C) Equator to poles
D) West to east
Answer: B
Explanation: Trade winds blow towards the equator from subtropical highs.
91. The westerlies are strongest in____________.
A) Summer
B) Winter
C) Equinoxes
D) Monsoon
Answer: B
Explanation: Westerlies strengthen during winter due to steep pressure gradients.
92. The layer where temperature remains almost constant with altitude is____________.
A) Troposphere
B) Tropopause
C) Stratosphere (lower)
D) Mesosphere
Answer: B
Explanation: Tropopause has isothermal conditions (constant temperature).
93. Atmospheric humidity is measured in____________.
A) Percentage
B) Grams per cubic meter
C) Millibars
D) Both (a) and (b)
Answer: D
Explanation: Humidity is measured as relative humidity (%) or absolute humidity (g/m³).
94. The unit of solar radiation energy is____________.
A) Lumen
B) Joule per square meter
C) Hertz
D) Newton
Answer: B
Explanation: Insolation is measured in J/m².
95. The main reason for atmospheric circulation is____________.
A) Earth’s shape
B) Unequal heating of Earth’s surface
C) Earth’s gravity
D) Ozone depletion
Answer: B
Explanation: Temperature and pressure differences drive atmospheric circulation.
96. The Coriolis force is maximum at____________.
A) Equator
B) 30° latitude
C) 45° latitude
D) Poles
Answer: D
Explanation: Coriolis effect increases with latitude, maximum at poles.
97. Which gas in the atmosphere is measured by the Keeling Curve?
A) Oxygen
B) Nitrogen
C) Carbon dioxide
D) Methane
Answer: C
Explanation: The Keeling Curve shows long-term CO₂ concentration trends.
98. The highest pressure belts are found at____________.
A) Equator
B) 30° latitudes
C) 60° latitudes
D) Poles
Answer: D
Explanation: Polar regions are high-pressure belts due to descending cold air.
99. The lowest pressure belt is found at____________.
A) Equator
B) 30° latitude
C) 60° latitude
D) Poles
Answer: A
Explanation: The equatorial low-pressure belt forms due to intense heating.
100. Which gas is critical for shielding Earth from UV rays?
A) Oxygen
B) Ozone
C) Nitrogen
D) Argon
Answer: B
Explanation: Ozone layer protects life by absorbing harmful UV radiation.