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Class 9 Social Science: Atmosphere and Climate, 8 practice questions with answers

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Here are 8 practice questions on Chapter 3 of the new NCERT Class 9 Social Science textbook, Understanding Society: India and Beyond (Part 1, First Edition 2026): Atmosphere and Climate. It is the book's second Geography chapter, after Shaping of the Earth's Surface. Every question has a worked answer and the textbook page behind it. They cover the gases in the air, how high each layer reaches, what happens in which layer, weather and climate, reading air pressure, land and sea breezes, India's traditional seasons, and the causes of the 2025 Punjab floods.

These questions are our own, drafted with AI help. Every number was re-computed by a script and every answer was checked against the chapter, but no practising teacher has reviewed them yet. None of them is one of the chapter's end-of-chapter questions reworded. If you find a mistake, please tell us.

What the chapter says you need

Facts from Chapter 3 of the NCERT textbook (Understanding Society: India and Beyond, the Grade 9 book, Part 1, printed pages 39 to 59):

Air and its layers

Question 1. Fig. 3.2 in the chapter gives the share of each gas in the atmosphere: nitrogen 78%, oxygen 21%, argon 0.93%, carbon dioxide 0.04% and others 0.03%. (a) Show that these five shares add up to 100%. (b) In a made-up sample of 1,000 litres of dry air, how many litres of nitrogen, oxygen and argon are there? (c) The chapter says water vapour is usually between 0.1 and 0.4 per cent of the air. In a made-up 500-litre sample, between how many litres is that?

Answer: (a) 78 + 21 + 0.93 + 0.04 + 0.03 = 100; (b) 780 litres of nitrogen, 210 of oxygen and 9.3 of argon; (c) between 0.5 and 2 litres. (a) 78 + 21 = 99, and 0.93 + 0.04 + 0.03 = 1.00, so the total is 100% (page 40, Fig. 3.2). (b) 1,000 × 78 ÷ 100 = 780; 1,000 × 21 ÷ 100 = 210; 1,000 × 0.93 ÷ 100 = 9.3. (c) 500 × 0.1 ÷ 100 = 0.5 and 500 × 0.4 ÷ 100 = 2. The amount changes from place to place and day to day, and water vapour matters for clouds and rain (page 40).

Question 2. A made-up weather balloon rises from the ground to a height of 90 km. Use the heights in the chapter: the troposphere reaches about 12 km on average, the stratosphere goes up to 50 km, the mesosphere up to 80 km, and the thermosphere runs from 80 to 700 km. (a) In what order does the balloon pass through the layers, and in which layer does it stop? (b) How thick is the stratosphere, and how thick is the mesosphere? (c) In which two layers does it get colder as the balloon goes up?

Answer: (a) troposphere, stratosphere, mesosphere, then it stops in the thermosphere; (b) the stratosphere is about 38 km thick and the mesosphere 30 km; (c) the troposphere and the mesosphere. (a) 90 km is above the 80 km top of the mesosphere and below 700 km, so the balloon ends in the thermosphere, crossing the tropopause, the stratopause and the mesopause on the way (pages 41-42). (b) 50 − 12 = 38 km and 80 − 50 = 30 km. (c) The chapter says temperature falls with height only in these two layers; in the thermosphere it climbs very fast, because the gases there take in X-rays and short-wave ultraviolet light from the Sun (page 42).

Question 3. Name the layer of the atmosphere where each of these happens: (a) hail falls during a storm; (b) a meteor burns up; (c) a layer of ozone filters out harmful ultraviolet rays; (d) radio waves sent up from the ground are bounced back down; (e) light gases such as helium and hydrogen drift off into space; (f) the northern lights glow in the sky.

Answer: (a) troposphere; (b) mesosphere; (c) stratosphere; (d) thermosphere; (e) exosphere; (f) thermosphere. (a) Almost all weather, including rain, fog and hail, happens in the troposphere (page 41). (b) Most meteorites from space burn up in the mesosphere. (c) The ozone layer is in the stratosphere. (d) The thermosphere, which includes the ionosphere, reflects radio waves back to the Earth. (f) The auroras also happen in the thermosphere (all page 42). (e) In the exosphere the air is very thin and gravity is weak, so light gases escape (page 43).

Weather, pressure and wind

Question 4. Say whether each sentence is about weather or about climate: (a) "It is foggy in our town this morning." (b) "Over the last 30 years, our city's average January temperature has been 14 °C." (c) "It will rain this evening." (d) "This coastal region is warm and wet for most of the year, year after year." Then: (e) a made-up weather station has kept records since 2016. Is ten years of records enough to describe the place's climate in the chapter's sense?

Answer: (a) weather; (b) climate; (c) weather; (d) climate; (e) no. Weather is the condition of the air from hour to hour and day to day, so (a) and (c) are weather. Climate is the average of the weather over a large area and a long time, usually thirty years or more, so (b) and (d) are climate (page 43). (e) Ten years is far short of the thirty or more that the chapter gives (page 43).

Question 5. On a made-up weather map, the air pressure reads 1012 at town P, 1004 at town Q and 996 at town R (made-up readings, like the numbers on the chapter's Fig. 3.7). (a) Between P and R, which way does the wind blow? (b) Which of the three towns is most likely to have cloudy, wet weather, and which clear skies? (c) A wind blowing from the east has what name? (d) Using Table 3.1, a wind of 45 km per hour is which kind of wind, and what does it do?

Answer: (a) from P towards R; (b) R is most likely cloudy and wet, P most likely clear; (c) an easterly; (d) a strong breeze: large branches sway and umbrellas are hard to use. (a) Air always moves from high pressure to low pressure, and 1012 is higher than 996 (page 45). (b) Low pressure goes with cloudy skies and wet weather, and high pressure with clear, sunny skies (page 45). (c) Winds are named after the direction they come from, so a wind from the west is a westerly and one from the east an easterly (page 45). (d) 45 lies between 39 and 49 km per hour, the strong breeze row of Table 3.1 (page 46).

Question 6. At a made-up seaside town on a sunny day: (a) which way does the local wind blow at 3 in the afternoon, and what is it called? (b) Which way does it blow at 2 in the morning, and what is it called? (c) Which of the two is usually gentler, and why?

Answer: (a) from the sea to the land, a sea breeze; (b) from the land to the sea, a land breeze; (c) the land breeze. (a) In the afternoon the land is warmer than the sea, so low pressure forms over the land and the wind blows in from the sea (page 46). (b) After dark the land loses its heat more quickly than the water does, so the wind turns and blows out to sea (page 46). (c) At night the gap in temperature and air pressure between land and sea is small, so the land breeze blows slowly (page 46). The chapter adds that these two breezes keep the climate of coastal areas moderate (page 46).

Seasons and change

Question 7. Table 3.2 in the chapter lists six traditional Indian seasons (ṛtus), each about two months long. (a) Which ṛtu does each of these fall in: the first week of April, the middle of August, early November, late January? (b) Show how twelve months give six seasons of two months each. (c) The chapter says the hottest month is not the same everywhere in India. Which is it in the west and south, and which in the north?

Answer: (a) April: Vasanta; August: Varṣhā; November: Hemanta; January: Śhiśhira; (b) 12 ÷ 6 = 2; (c) April in the west and south, May in the north. (a) By Table 3.2, Vasanta covers March-April, Varṣhā July-August, Hemanta November-December and Śhiśhira January-February (page 48). The table also notes that the seasons and their length can differ across the country. (b) The traditional seasons divide the twelve months into six parts (page 48). (c) In the summer or pre-monsoon season, April is the hottest month in the western and southern regions, and May in the northern regions (page 47).

Question 8. The chapter's case study of the 2025 Punjab floods lists natural and human-made causes. (a) Sort these into the two groups: very heavy monsoon rain, made worse by western disturbances; old, weak river embankments; homes and farms built too close to the rivers; rivers already running high before the heavy rain; silt and mud built up in rivers and dams; flood warnings that came late or were unclear. (b) Name the four greenhouse gases the chapter lists, and say what they do.

Answer: (a) natural: the heavy rain and western disturbances, and the rivers already running high; human-made: the weak embankments, building too close to the rivers, the silt in rivers and dams, and the late warnings; (b) carbon dioxide, methane, nitrous oxide and water vapour; they trap heat and raise the temperature of the globe. (a) The chapter puts the rain, made heavier by western disturbances, and the high rivers (the Satluj, Beas, Ravi and Ghaggar) under natural causes. Old embankments (dhūsī bāndh), building on the space floodwater needs, silt cutting the rivers' and dams' capacity, and late or unclear warnings come under human-made causes (page 55). (b) Burning fossil fuels, cutting forests and industrial pollution add these gases to the air, and that drives climate change (page 53).

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Sources

All opened and read on 3 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 38.

The facts, Fig. 3.2 and Tables 3.1 and 3.2 are from the textbook pages above; Fig. 3.2 was read from the rendered page. The questions, the made-up figures and the worked answers are our own, and every number was re-computed by script. This guide is general information; follow your teacher and the textbook.

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