Looking for an exam-oriented collection of Multiple Choice Questions (MCQs) for SEBA Class 9 Social Science Geography Chapter 2 (Atmosphere: Structure, Air Pressure and Wind System / বায়ুমণ্ডল: গঠন, বায়ুৰ চাপ আৰু বায়ু প্ৰবাহ) for the 2026–27 academic session? Access chapter-wise objective questions with verified answers, matching pairs, and assertion-reason items. Master key atmospheric concepts covering atmospheric gas percentages (Nitrogen 78.08%, Oxygen 20.94%); vertical thermal layers (Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere); normal lapse rate (6.5°C drop per 1,000 meters); the ozone layer situated in the Stratosphere; transition pauses (Tropopause, Stratopause, Mesopause); instruments used to measure atmospheric pressure (mercury and aneroid barometers); standard sea-level pressure (1013.25 mb / 76 cm of mercury); global permanent pressure belts (Equatorial Low Pressure Doldrums, Subtropical High Pressure Horse Latitudes at 30°–35° N/S, Subpolar Lows at 60°–65° N/S, and Polar Highs); Ferrel’s Law and Coriolis force deflection rules; permanent planetary wind systems (Trade Winds, Westerlies, Polar Easterlies); seasonal and periodic winds (South-West and North-East Monsoons, land and sea breezes, mountain and valley winds); local winds around the globe (Loo, Chinook, Foehn, Mistral, Sirocco); tropical vs. extra-tropical cyclone dynamics and anticyclone pressure traits, designed strictly according to the Assam Board (SEBA) Class 9 objective examination curriculum.
Q.1. Up to what vertical altitude does the atmosphere extend from the earth’s surface?
A. 1,000 km
B. 5,000 km
C. 10,000 km
D. 20,000 km
Answer: C. 10,000 km
Q.2. Which force keeps the atmosphere attached to the earth?
A. Centrifugal force
B. Gravitational force
C. Magnetic force
D. Frictional force
Answer: B. Gravitational force
Q.3. What is the volumetric percentage of nitrogen in the atmosphere?
A. 20.94%
B. 78.08%
C. 0.93%
D. 0.036%
Answer: B. 78.08%
Q.4. What is the volumetric percentage of oxygen in the atmosphere?
A. 78.08%
B. 20.94%
C. 0.93%
D. 1.05%
Answer: B. 20.94%
Q.5. What is the volumetric percentage of argon in the atmosphere?
A. 0.036%
B. 0.14%
C. 0.93%
D. 1.20%
Answer: C. 0.93%
Q.6. What is the volumetric percentage of carbon dioxide in the earth’s atmosphere?
A. 0.036%
B. 0.36%
C. 0.003%
D. 0.93%
Answer: A. 0.036%
Q.7. Heavier atmospheric gases like nitrogen and oxygen are mostly confined to an altitude of:
A. 10 to 20 km
B. 40 to 50 km
C. 80 to 100 km
D. 200 to 300 km
Answer: C. 80 to 100 km
Q.8. Which gas is chemically inactive and commonly used in electric bulbs and welding?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Argon
Answer: D. Argon
Q.9. What is the average surface temperature maintained on earth by the heat absorption of carbon dioxide?
A. 10°C
B. 15°C
C. 20°C
D. 25°C
Answer: B. 15°C
Q.10. At what altitude is the protective ozone gas primarily concentrated?
A. 10–16 km
B. 20–30 km
C. 40–50 km
D. 80–100 km
Answer: C. 40–50 km
SEBA Class 9 Geography Chapter 2 MCQ
Q.11. The lower atmospheric zone extending up to 80 km where chemical composition remains uniform is called:
A. Heterosphere
B. Homosphere
C. Exosphere
D. Ionosphere
Answer: B. Homosphere
Q.12. What percentage of the total mass of atmospheric elements is confined within an altitude of 32 km?
A. 50%
B. 75%
C. 90%
D. 99%
Answer: D. 99%
Q.13. The atmospheric layer situated above 80 km with layered chemical composition is called:
A. Homosphere
B. Troposphere
C. Heterosphere
D. Stratosphere
Answer: C. Heterosphere
Q.14. Which atomic layer in the Heterosphere extends up to an altitude of about 10,000 km?
A. Nitrogen layer
B. Oxygen layer
C. Helium layer
D. Hydrogen layer
Answer: D. Hydrogen layer
Q.15. What is the average height of the Troposphere?
A. 8 km
B. 12 km
C. 16 km
D. 20 km
Answer: B. 12 km
Q.16. What is the height of the Troposphere over the equatorial region?
A. 8 km
B. 12 km
C. 16 km
D. 25 km
Answer: C. 16 km
Q.17. What is the height of the Troposphere over the polar regions?
A. 8 km
B. 12 km
C. 16 km
D. 4 km
Answer: A. 8 km
Q.18. How much of the total atmospheric gas volume is contained in the Troposphere alone?
A. One-half
B. Two-thirds
C. Three-fourths
D. Nine-tenths
Answer: C. Three-fourths
Q.19. The normal lapse rate of temperature in the Troposphere is a decrease of:
A. 5.5°C per km
B. 6.5°C per km
C. 7.5°C per km
D. 10°C per km
Answer: B. 6.5°C per km
Q.20. What is the approximate thickness of the Tropopause?
A. 0.5 km
B. 1.0 km
C. 1.5 km
D. 3.0 km
Answer: C. 1.5 km
Atmosphere Structure Air Pressure and Wind System Multiple Choice Questions SEBA 2026-27
Q.21. What temperature is reached at the Tropopause?
A. 0°C
B. -45°C
C. -60°C
D. -100°C
Answer: C. -60°C
Q.22. The Stratosphere extends upward from the Tropopause for about:
A. 20 km
B. 30 km
C. 40 km
D. 60 km
Answer: C. 40 km
Q.23. The combined average height of the Troposphere and Stratosphere together from the earth’s surface is about:
A. 32 km
B. 50 km
C. 80 km
D. 100 km
Answer: B. 50 km
Q.24. In the Stratosphere, the air temperature rises from -60°C to approximately:
A. -30°C
B. 0°C
C. 15°C
D. 32°C
Answer: B. 0°C
Q.25. The boundary marking the upper limit of the Stratosphere is called:
A. Tropopause
B. Stratopause
C. Mesopause
D. Thermopause
Answer: B. Stratopause
Q.26. The Mesosphere extends from the Stratopause for an additional height of:
A. 20 km
B. 30 km
C. 50 km
D. 80 km
Answer: B. 30 km
Q.27. At the Mesopause (altitude of about 80 km), temperature drops to a minimum of:
A. -60°C
B. -80°C
C. -100°C
D. -150°C
Answer: C. -100°C
Q.28. The Thermosphere extends from 80 km up to:
A. 200 km
B. 400 km
C. 600 km
D. 1,000 km
Answer: B. 400 km
Q.29. Why is the Thermosphere also referred to as the Ionosphere?
A. It contains water vapour
B. It contains ozone gas
C. It contains electrically charged ions
D. It has dense clouds
Answer: C. It contains electrically charged ions
Q.30. In the Exosphere, air temperature can reach up to about:
A. 1,200°C
B. 1,650°C
C. 3,540°C
D. 5,550°C
Answer: D. 5,550°C
Class 9 Social Science Geography Chapter 2 MCQ Solutions
Q.31. What is the average atmospheric pressure per square inch at mean sea level?
A. 10.5 Pounds
B. 14.7 Pounds
C. 18.2 Pounds
D. 29.9 Pounds
Answer: B. 14.7 Pounds
Q.32. Normal atmospheric pressure at sea level corresponds to a mercury column height of:
A. 76 cm (29.92 inches)
B. 70 cm (27.55 inches)
C. 80 cm (31.50 inches)
D. 100 cm (39.37 inches)
Answer: A. 76 cm (29.92 inches)
Q.33. The average atmospheric pressure at sea level expressed in millibars (mb) is:
A. 980.5 mb
B. 1000.0 mb
C. 1013.2 mb
D. 1032.4 mb
Answer: C. 1013.2 mb
Q.34. One inch of mercury level in a barometer is equal to approximately how many millibars?
A. 14.7 mb
B. 29.9 mb
C. 33.9 mb
D. 76.0 mb
Answer: C. 33.9 mb
Q.35. Which instrument automatically records air pressure on a graph?
A. Barometer
B. Barograph
C. Anemometer
D. Altimeter
Answer: B. Barograph
Q.36. For every 900 feet increase in altitude, atmospheric pressure decreases by approximately:
A. 0.5 inch (17 mb)
B. 1 inch (34 mb)
C. 2 inches (68 mb)
D. 3 inches (100 mb)
Answer: B. 1 inch (34 mb)
Q.37. The Equatorial Low Pressure Belt lies between:
A. 0° and 5° North and South
B. 10° N and 10° S latitudes
C. 15° N and 25° N latitudes
D. 25° N and 35° S latitudes
Answer: B. 10° N and 10° S latitudes
Q.38. The Equatorial Low Pressure Belt is popularly known as:
A. Horse Latitudes
B. Roaring Forties
C. Doldrums
D. Polar Front
Answer: C. Doldrums
Q.39. Sub-Tropical High Pressure Belts are located between:
A. 10° and 20° North and South latitudes
B. 25° and 35° North and South latitudes
C. 40° and 50° North and South latitudes
D. 60° and 70° North and South latitudes
Answer: B. 25° and 35° North and South latitudes
Q.40. Why were the sub-tropical high-pressure belts named ‘Horse Latitudes’?
A. Horses were bred in this calm region
B. Navigators threw horses into the sea to lighten ships
C. Fast winds resembled running horses
D. Trade routes traded only horses
Answer: B. Navigators threw horses into the sea to lighten ships
Assam Board Class 9 Geography Chapter 2 Solved MCQ PDF
Q.41. The Sub-Polar Low Pressure Belts are located roughly between:
A. 30° and 45° North and South latitudes
B. 50° and 60° North and South latitudes
C. 60° and 70° North and South latitudes
D. 75° and 85° North and South latitudes
Answer: C. 60° and 70° North and South latitudes
Q.42. Air moves naturally from:
A. Low pressure to high pressure
B. High pressure to low pressure
C. Sea level to mountain top only
D. Equator to poles only
Answer: B. High pressure to low pressure
Q.43. According to Ferrel’s Law, winds deflect towards the right in the:
A. Southern Hemisphere
B. Northern Hemisphere
C. Equatorial zone
D. Polar circle
Answer: B. Northern Hemisphere
Q.44. The Coriolis force is maximum at the:
A. Equator
B. Tropic of Cancer
C. Poles
D. Sub-tropics
Answer: C. Poles
Q.45. The stormy Westerlies blowing between 40° and 50° S latitudes are known as:
A. Furious Fifties
B. Screaming Sixties
C. Roaring Forties
D. Doldrums
Answer: C. Roaring Forties
Q.46. The Westerly winds between 50° and 60° S latitudes are termed:
A. Roaring Forties
B. Furious Fifties
C. Screaming Sixties
D. Horse Latitudes
Answer: B. Furious Fifties
Q.47. Polar winds blow from the east in both hemispheres, so they are known as:
A. Polar Westerlies
B. Polar Easterlies
C. Jet Streams
D. Trade Winds
Answer: B. Polar Easterlies
Q.48. Jet Streams blow towards which direction at high altitudes in the upper troposphere?
A. West
B. North
C. East
D. South
Answer: C. East
Q.49. What is an elongated cell of high pressure called?
A. Trough
B. Ridge
C. Eye
D. Front
Answer: B. Ridge
Q.50. In an anticyclone in the Northern Hemisphere, winds blow:
A. Inward and clockwise
B. Inward and anticlockwise
C. Outward and clockwise
D. Outward and anticlockwise
Answer: C. Outward and clockwise
🌤️ Class 9 Social Science MCQ Practice Notice: This page features an exhaustive set of SEBA Class 9 Social Science (Geography Section) Chapter 2: Atmosphere: Structure, Air Pressure and Wind System Multiple Choice Questions (MCQs) with Verified Answers updated for the 2026–27 academic session. Structured according to the latest Assam Board objective examination pattern, these questions test numerical values, atmospheric boundaries, and physical climatology facts—covering atmospheric gas composition, thermal layers from the Troposphere to Exosphere, global permanent pressure belts, deflection under Ferrel’s Law, planetary and periodic winds, and cyclonic circulation patterns—to help you secure full marks in Section A of your school unit tests, half-yearly exams, and final annual examinations.
💡 Ace Your Class 9 Geography Objective Assessments:
- Confused about the exact latitude zone of the Subtropical High-Pressure Belts or Horse Latitudes (30°–35° N/S), which atmospheric layer reflects radio waves back to Earth (Ionosphere / Thermosphere), the rate of the standard environmental lapse rate (6.5°C per km), or the direction of wind rotation in a Northern Hemisphere cyclone (anticlockwise)? Leave your query in the comments section below!
- Bookmark this page to test your speed and factual accuracy on pressure gradients, wind systems, and atmospheric layers before your upcoming unit evaluations, half-yearly exams, and final annual examinations.
- Share this link with your classmates and WhatsApp study groups to practice and master Class 9 Social Science climatology objective questions together!