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Class 9 Social Science: Shaping of the Earth's Surface, 8 practice questions with answers

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Here are 8 practice questions on Chapter 2 of the new NCERT Class 9 Social Science textbook, Understanding Society: India and Beyond (Part 1, First Edition 2026): Shaping of the Earth's Surface. It is the first Geography chapter of the book. Every question has a worked answer and the textbook page behind it. They cover how far a plate moves, the Earth's layers in Fig. 2.1, the three kinds of plate boundary, weathering and erosion, what a river builds along its course, coasts, glaciers, wind and underground water, and the four disasters the chapter links to landforms.

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 15 end-of-chapter questions reworded. If you find a mistake, please tell us.

What the chapter says you need

Facts from Chapter 2 of the NCERT textbook (Understanding Society: India and Beyond, the Grade 9 book, Part 1, printed pages 13 to 38):

Plates and the Earth's layers

Question 1. The chapter says tectonic plates usually move a few centimetres a year (page 14). Take a made-up plate that moves 5 cm a year. (a) How far does it move in 1,000 years, in metres? (b) How far in one million years, in kilometres? (c) Over which layer do the plates slide? (d) The chapter names three types of plate. Which type carries both a continent and an ocean floor?

Answer: (a) 50 metres; (b) 50 kilometres; (c) the asthenosphere; (d) a mixed plate. (a) 5 × 1,000 = 5,000 cm, and 5,000 ÷ 100 = 50 m. (b) 5 × 1,000,000 = 5,000,000 cm = 50,000 m, and 50,000 ÷ 1,000 = 50 km. A movement too slow to notice in a lifetime still adds up to a long way. (c) The plates sit on the asthenosphere, which is semi-molten and lets them move (page 14). (d) Continental plates carry continents and oceanic plates carry ocean floors; a plate that carries both is a mixed plate (page 14).

Question 2. Fig. 2.1 in the chapter gives approximate thicknesses: 5 km for the crust under an ocean, 30 km for the crust under a continent, and 100 km for the lithosphere (page 14). (a) How many times thicker is the continental crust than the oceanic crust? (b) The lithosphere is the crust plus the upper part of the mantle. Using the figure's values, how many of the lithosphere's 100 km are upper mantle under an ocean, and how many under a continent? (c) Which layer does the figure call a fluid, and what is it mainly made of? Which part does it call the densest?

Answer: (a) 6 times; (b) 95 km under an ocean and 70 km under a continent; (c) the outer core, mainly iron and nickel; the inner core. (a) 30 ÷ 5 = 6. (b) 100 − 5 = 95 and 100 − 30 = 70 (page 14). The figure says its values are approximate, and its note on the crust gives ranges, 30-40 km under continents and 5-7 km under the ocean, so real answers vary. (c) The figure describes the outer core as a fluid layer mainly of iron and nickel, and the inner core as a solid, spinning ball of hot metal, the densest part of our planet (page 14).

Question 3. For each of these, name the kind of plate boundary and say what happens to the crust there: (a) the Himalaya; (b) the Mid-Atlantic Ridge; (c) the San Andreas Fault (USA); (d) an oceanic plate meeting a continental plate.

Answer: (a) convergent, two continental plates collide and fold up into mountains; (b) divergent, magma rises and makes new crust; (c) transform, the plates slide past each other and no crust is made or destroyed; (d) convergent, the ocean plate goes down under the continental one. (a) Plates moving towards each other meet at a convergent boundary; two continental plates pushing into each other crumple up into fold mountains, the Himalaya being one. (b) At a divergent boundary the plates move apart, magma rises and forms new crust, building mid-ocean ridges. (c) A transform boundary mainly causes earthquakes. (d) This is also a convergent boundary, and it leads to volcanoes and earthquakes (all page 15).

Weathering, erosion and running water

Question 4. Decide whether each of these is weathering or erosion, and if it is weathering, say which of the three types: (a) a tree's roots grow into a crack and split a rock; (b) a rock face cracks after years of hot days and cold nights; (c) rainwater reacts with the minerals in a rock and turns them into a new substance; (d) a river carries soil from a hillside down to the plains; (e) sea waves wear away the land along the shore.

Answer: (a) biological weathering; (b) physical weathering; (c) chemical weathering; (d) erosion, by water; (e) erosion, along the coast. The test the chapter gives is movement: weathering only breaks rock down where it lies, while erosion carries the broken material from one place to another (pages 19-20). (a) Plant roots splitting rock is the chapter's own example of biological weathering. (b) Temperature changes break rock into pieces: physical weathering. (c) Reactions with water, air or acids that form new substances are chemical weathering (page 20). (d) and (e) The material moves, so this is erosion: water erosion by rivers, and coastal erosion by waves (page 20).

Question 5. (a) Sort these into the upper, middle and lower course of a river: delta, V-shaped valley, meander, levee, waterfall, oxbow lake, rapids, alluvial fan, floodplain. (b) On a meander, which bank does the river wear away, and where does it leave sediment? (c) Why does a waterfall form where it does?

Answer: (a) upper course: V-shaped valley, waterfall, rapids; middle course: meander, oxbow lake, floodplain; lower course: delta, levee, alluvial fan; (b) it wears away the outer bank of each bend and drops sediment on the inner bank; (c) hard rock resists erosion while the softer rock below it is worn away, leaving a sudden drop. (a) The steep upper course erodes strongly; in the middle course the river begins to bend in loops and drop sediment as it loses energy; in the lower course it slows down even more and drops a great deal of sediment (page 22). (b) Eroding the outer bank and depositing on the inner bank slowly makes the loops larger (page 24). (c) Waterfalls form in the upper course for this reason, and some are used to make hydroelectric power (pages 22-23).

Coasts, glaciers, wind and underground water

Question 6. (a) Put these three coastal landforms in the order in which they form, and say how each one leads to the next: stack, cave, arch. (b) Which is made by waves depositing material, and which by waves wearing land away: a beach, a sea cliff, a wave-cut platform? (c) Give two ways the chapter says beaches are useful to people.

Answer: (a) cave, then arch, then stack; (b) the beach is made by deposition, the sea cliff and the wave-cut platform by erosion; (c) any two of: tourism, fishing, collecting sand and shells, and protection from strong waves and coastal erosion. (a) Waves erode weak parts of the rock to make caves; when two caves, one on each side of a headland, join up, they make an arch; when the arch collapses, an isolated pillar of rock, the stack, is left standing (page 26). (b) A beach is built from sediments the waves deposit (page 25). A cliff is a steep rock face left where waves cut in at the bottom of the coast, and the wave-cut platform is the flat area left behind as the cliff retreats (page 26). (c) Beaches bring tourists, support fishing and the collecting of sand and shells, and act as natural barriers that help protect settlements near the coast (page 25).

Question 7. (a) Match each landform to the agent that made it (glaciers, wind or underground water): cirque, yardang, stalactite, arete, barchan dune, sinkhole, fjord, moraine. (b) How is a stalactite different from a stalagmite? (c) How is a barchan dune different from a star dune?

Answer: (a) glaciers: cirque, arete, fjord, moraine; wind: yardang, barchan dune; underground water: stalactite, sinkhole; (b) a stalactite hangs from the ceiling of a cave, a stalagmite rises from its floor; (c) a barchan is crescent-shaped and forms where sand is limited and the wind blows from one direction; a star dune has several arms and forms where winds come from different directions. (a) Cirques are bowl-shaped hollows at the head of a glacier, aretes are sharp ridges between valleys, fjords are glacial valleys flooded by the sea (page 27), and moraines are the rock and soil a glacier leaves behind when it melts (page 28). Yardangs are streamlined rock ridges carved by wind (page 29), and dunes are hills of sand shaped by wind (page 30). Stalactites and sinkholes belong to karst landforms made where underground water dissolves limestone (pages 31-32). (b) and (c) pages 31 and 30.

Landforms and disasters

Question 8. Here are four made-up reports. (a) Name the disaster in each: (i) after a week of heavy rain, a hillside cut back for a new road gives way and blocks it; (ii) a steep snow slope gets a lot of fresh snow in two days, then a sudden warm spell, and the snow slides down; (iii) a lake held back by a wall of moraine fills fast as the glacier above it melts, and the wall bursts; (iv) after a long drought on overgrazed land, strong winds lift dry soil high into the air. (b) For three of these four, the chapter also names human activities that add to the risk. Which three, and give one such activity for each.

Answer: (a) (i) a landslide, (ii) an avalanche, (iii) a glacial lake outburst flood (GLOF), (iv) a dust storm; (b) landslides (deforestation, mining, road building or unplanned building on hillsides), avalanches (skiing, trekking or construction in the mountains) and dust storms (deforestation, overgrazing or poor farming that leaves little plant cover). (a) (i) Heavy rain adds weight to the soil and reduces friction, and steep or loose slopes add to the risk (page 33). (ii) Heavy snowfall in a short time and a sudden rise in temperature both make snow unstable (page 34). (iii) Fast glacier melt raises the lake and presses on its natural dam of ice or loose moraine until it collapses (page 35). (iv) Drought dries the soil so strong winds can lift it (page 36). (b) For GLOFs the chapter gives only natural and climatic causes, such as rising temperatures, heavy rain or snow, and earthquakes, avalanches or landslides striking the lake (pages 33-36).

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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 + 12.

The facts and Fig. 2.1 values are from the textbook pages above; Fig. 2.1 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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