CBSE Class 9 Social Science Chapter 02 Shaping Of The Earths Surface MCQs Set 03

Answer: (A) It is thicker under continents (30-40 km) than under oceans (5-7 km)

Explanation:
The chapter's diagram of Earth's interior gives continental crust as roughly 30 km and oceanic crust as only about 5 km, confirming that land areas sit on a much thicker slab of crust than ocean floors do.

Answer: (A) Minerals in rocks reacting with water, air, or acids to form new substances

Explanation:
That's the textbook's own description of chemical weathering. Freezing/thawing and wind action fall under physical weathering, while root growth is biological weathering.

Answer: (A) A rock breaking apart after repeated temperature swings and frost action

Explanation:
Physical weathering is caused by temperature change, frost, or wind acting on rock. Dissolving minerals is chemical weathering, root splitting is biological weathering, and wave action on a cliff is erosion, not weathering, since it moves material away.

Answer: (A) A rock that has been polished and reshaped by wind-driven sand

Explanation:
Ventifacts are described as rocks shaped through sandblasting by wind. The other options describe a yardang, a deflation hollow, and a desert pavement respectively — all separate wind-formed features mentioned in the same passage.

Answer: (A) Most earthquakes and volcanoes cluster along tectonic plate boundaries, especially around the Pacific

Explanation:
• The chapter states most seismic and volcanic activity happens along plate edges.
• This concentration around the Pacific Ocean is specifically named the Ring of Fire.
• The Let's Explore activity asks students to verify exactly this overlap using the two maps.

Answer: (A) They serve as natural harbours and support fishing activities

Explanation:
Fjords are deep, narrow sea inlets formed when the ocean floods glacial valleys, and the chapter notes they are useful for harbours and fishing — unlike glacial soil, which is instead linked to farming in valleys.

Answer: (A) Tourism and fishing, since beaches, rivers, and fertile land can be washed away

Explanation:
The passage on erosion's effects on human occupations lists farming, construction, mining, and then adds tourism and fishing as further sectors that suffer when beaches, rivers, and fertile lands are destroyed.

Answer: (A) A flat surface exposed at the base of a cliff as the cliff line gradually retreats

Explanation:
Wave-cut platforms are flat areas left behind as sea cliffs are worn back over time. The other options instead describe a sea stack, a sand bar, and a sea cave — distinct features covered in the same coastal section.

Answer: (A) Caribbean Plate

Explanation:
• The chapter names the Pacific, Eurasian, African, North American, South American, Indo-Australian, and Antarctic plates as the major ones.
• The Caribbean Plate is a real tectonic plate in geography generally, but it is never mentioned in this chapter's list.
• This makes it the odd one out here.

Answer: (A) Glacier

Explanation:
The definition box lists mountains, valleys, plateaus, plains, deserts, and coastal features as examples of landforms. A glacier is instead treated later in the chapter as an agent of gradation that shapes such landforms, not as a landform itself.

Answer: (A) Detailed rules for assessing and categorising land according to fertility and productivity

Explanation:
This detail appears in the box about the Sindhu-Sarasvati civilisation's water-management heritage, where the Arthashastra is credited with laying down guidelines for judging land quality and productivity.

Answer: (A) Building earthen embankments along contour lines to slow run-off and reduce soil erosion

Explanation:
Bunding refers specifically to earthen embankments along contours. The other choices describe contour trenching, terracing, and check dams, which are separate conservation methods mentioned nearby.

Answer: (A) Because it destabilises land, raising the risk of accidents and collapses

Explanation:
The chapter directly states that erosion destabilises land in construction and mining contexts, creating safety hazards for people working there.

Answer: (A) Yardang

Explanation:
Yardangs are streamlined rock ridges carved by wind, placed under the section on wind erosion. Sea caves, sand bars, and sea stacks, by contrast, are all listed as coastal features produced by wave and current action.

Answer: (A) Star dunes have multiple arms formed by winds from several directions, while parabolic dunes are U-shaped and held in place by vegetation

Explanation:
Star dunes develop their multiple arms where winds blow from different directions, whereas parabolic dunes take a U-shape and are often anchored by plant growth — a clearly different formation process from the crescent-shaped barchan dunes described elsewhere in the same passage.

Answer: (A) The rigid layer formed by the crust together with the upper part of the mantle

Explanation:
The lithosphere combines the crust and the topmost part of the mantle into one rigid shell, and it is this shell that is broken up into the tectonic plates. The semi-molten layer below it, which lets plates slide, is instead called the asthenosphere.

Answer: (A) A cirque

Explanation:
This depression forms right where a glacier originates and begins carving into the mountainside. Aretes are the sharp ridges left between two such glacial valleys, not the hollow itself, while fjords are sea-flooded valleys and moraines are deposits of debris.

Answer: (A) Till

Explanation:
The chapter names this glacially transported debris 'till'; when the ice melts, this material is left behind as ridges called moraines along the sides, middle, or end of the glacier's path.

Answer: (A) Gujarat

Explanation:
The chapter presents an image of extensive destruction from the 2001 earthquake in Gujarat to illustrate India's vulnerability to seismic disasters in densely populated areas.

Answer: (A) Plate boundaries

Explanation:
These contact zones are called plate boundaries, and the chapter groups them into three kinds—convergent, divergent, and transform—each producing its own set of landforms and hazards.

Answer: (B) A crescent-shaped ridge of sand built up by a single-direction wind

Explanation:
Wind does not just build features like dunes; it also scoops out material, leaving shallow depressions called deflation hollows or blowouts. A rock polished by blown sand is instead a ventifact, and a flat surface stripped of fine grains is a desert pavement.

Answer: (A) Longitudinal dunes

Explanation:
Longitudinal dunes stretch out in line with steady prevailing winds. Star dunes instead grow multiple arms where winds blow from several directions, and parabolic dunes curve into a U-shape once vegetation anchors them.

Answer: (A) They supply fresh water and offer opportunities for tourism and sometimes hold cultural significance

Explanation:
Caves and the rivers flowing through them give people access to fresh water, draw visitors and researchers, and in some places carry religious or cultural meaning, alongside the geological interest of stalactites and stalagmites found within them.

Answer: (A) Landslides, avalanches, GLOFs, and dust storms

Explanation:
• Landslides occur on unstable slopes weakened by rain or human activity
• Avalanches involve sudden snow slides on steep mountains
• GLOFs happen when glacial lakes burst their natural dams
• Dust storms arise from strong winds lifting loose, dry soil in arid regions

Answer: (A) It destroyed buildings, roads, bridges, and hydel projects, and cut off village connectivity

Explanation:
The flood in Chamoli district struck suddenly, killing people and livestock while wrecking infrastructure such as buildings, roads, bridges, and hydropower projects, and it left many villages cut off from the outside world.