CBSE · NCERT · Class 9 Social Science · Chapter 2

NCERT Solutions: Class 9 Social Science Chapter 2 - Shaping of the Earth’s Surface

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Chapter-wise NCERT intext questions and exercise answers for Shaping of the Earth’s Surface, grounded in the official textbook.

Questions are taken verbatim from the NCERT textbook; answers were grounded against the chapter's content during generation. Items needing review are marked.
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Questions and activities 9
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1Questions and activities9 questions
Q.1What are the sources of energy that are required to cause movements associated with the internal forces of the Earth?v
Solution

Grounded in the chapter’s explanation of endogenic forces and mantle movement.

Answer:

Internal movements are powered mainly by heat within the Earth, including residual heat from its formation and heat generated by radioactive decay. This heat drives convection in the mantle and the movement of lithospheric plates. Gravity and differences in density also contribute to the sinking, rising and adjustment of crustal material.

Q.2Relate various physiographic divisions you have studied in the earlier grades with various endogenic forces responsible for their origin.v
Solution

Applies plate convergence, faulting, uplift and subsidence to India’s major divisions.

Answer:

The Himalayas formed when the Indian and Eurasian plates converged, compressing and folding sediments. The Peninsular Plateau is part of an ancient stable crustal block shaped by uplift, faulting and long erosion; rifting and faulting helped form features such as the Narmada–Tapi troughs and western coastal margin. The Andaman and Nicobar arc lies near a convergent boundary with tectonic and volcanic activity. The Northern Plains, although related to the Himalayan foredeep, were built mainly by river deposition and therefore show endogenic and exogenic processes working together.

Q.3Why and where do earthquakes occur frequently? Is it possible to predict earthquakes?v
Solution

Grounded in the earthquake mechanism, distribution and disaster discussion.

Answer:

Earthquakes occur when accumulated stress is suddenly released along faults as tectonic plates converge, diverge or slide past one another. They are therefore frequent near plate boundaries and active fault zones, including the Himalayan belt, northeast India, the Andaman–Nicobar region and the Kachchh area. Scientists can map hazard zones and monitor seismic activity, but they cannot yet predict the exact time, place and magnitude of an earthquake reliably.

Q.4“Plate movements are responsible for the distribution of earthquakes and volcanoes.” Explain.v
Solution

The three boundary types explain the mapped distribution.

Answer:

Most earthquakes and volcanoes cluster along plate margins. At convergent margins one plate may descend, melt and feed volcanoes while friction produces strong earthquakes. At divergent margins rising magma creates new crust, volcanic activity and shallow earthquakes. At transform margins plates grind past one another and release stored stress as earthquakes. The belts around the Pacific and along mid-ocean ridges therefore reflect the global pattern of plate boundaries.

Q.6How are deforestation and erosion associated with each other? Explain.v
Solution

Grounded in the chapter’s erosion processes and vegetation role.

Answer:

Tree canopies reduce the force of rainfall, roots bind soil and vegetation slows surface runoff. Deforestation removes this protection, leaving loose soil exposed to rain and wind. Runoff then increases, carrying away topsoil and cutting rills or gullies; slopes may also become less stable and more prone to landslides. Erosion in turn makes natural regeneration harder by removing fertile soil.

Q.7Develop a plan to protect the land in your local area from erosion.v
Solution

Open-ended local plan applying the chapter’s vegetation, contour and drainage controls.

Answer:

A model plan begins by mapping bare slopes, drainage lines, construction sites and streambanks. Plant native grasses, shrubs and trees; use contour trenches or terraces on slopes; keep ground covered with mulch; stabilise streambanks; and route storm water through permeable drains and recharge pits. Restrict dumping, sand removal and grazing in vulnerable patches. Residents and the local body should inspect the sites before and after monsoon and repair small gullies before they expand.

Q.8Which disasters do you think you might experience in your region? Discuss a mitigation plan in your classroom.v
Solution

Open-ended regional response applying the chapter’s hazard, preparedness and mitigation framework.

Answer:

A model answer for many Indian urban regions is intense-rain flooding, heat waves and possible earthquake shaking. Mitigation should identify safe shelters and evacuation routes, keep drains clear, preserve wetlands, publish emergency contacts, practise school drills, secure heavy furniture, store water and first-aid supplies, and issue heat and rain alerts. The exact plan must be adjusted to the local hazard map rather than assuming every region faces the same risk.

Q.10What precautionary measures will you take if you are staying in an earthquake-prone region?v
Solution

Grounded in the chapter’s earthquake preparedness guidance.

Answer:

Before an earthquake, secure shelves and cylinders, identify safe spots away from glass, keep an emergency kit and practise evacuation. During shaking, drop, cover and hold under sturdy furniture; stay away from windows and lifts, and if outdoors move into an open area away from buildings and wires. Afterward, expect aftershocks, switch off leaking gas or electricity if safe, give first aid, use messages instead of congesting phone lines and follow official instructions.

Q.13Document a case of a disaster that hit your region in the past, highlighting its effects on various human activities.v
Solution

Sample documented case applying the chapter’s disaster-impact categories.

Answer:

A model case is the 2015 Chennai floods. Exceptional rain and overflowing water bodies inundated neighbourhoods, shut roads, rail and airport services, interrupted electricity and telecommunications, damaged homes and shops, stopped industrial and office work, and closed schools and hospitals. Rescue boats, community kitchens and volunteer networks became essential. The case shows how a physical hazard becomes a broad social and economic disaster when drainage, settlement patterns and preparedness are inadequate.