9th Social science unit 2 Assignment answer key - Geography Jyly 2021

9th Social science unit 2 Assignment answer key - Geography Jyly 2021


Class: 9 Subject: Social Science


UNIT 2- Lithosphere – II Exogenetic Processes

Part – A

I.One Mark Questions:

1.Peeling of Rocks is called…………….

a) Physical weathering

b) Chemical weathering

c) Soil erosion

d) Biological weathering

Answer: a) Physical weathering

2.The course of the river is divided into ……………

a) 4

b) 3

c) 2

d) 5

Answer: b) 3

3.Stacks are formed by……………

a) Wave erosion

b) River erosion

c) Glacial erosion

d) Wind deposition

Answer: a) Wave erosion

4.Crescent shaped sand dunes are called ……………

a) Inselberg

b) Yardang

c) Barchan

d) Sand dunes

Answer: c) Barchan

5…………….. is seen in the lower course of the river.

a) Rapids

b) Alluvial fan

c) Delta

d) Gorges

Answer: c) Delta

Fill in the blanks:

1.Broken rocks become …………… due to weathering.

  • Answer: decomposition

2.…………… occurs due to the penetration of plant roots into the rocks.

Answer: Biological weathering

3.The highest waterfall in the World is ……………

Answer: Angel falls in venezuela

4.A triangular shaped low lying area formed by the river is called ……………

Answer: Delta

5.Inselberg is a German term which means …………….

Answer: island mountain

Part – B

II. Short Answer.

1.Define Weathering.

  • Weathering is the disintegration and decomposition of materials of the earth’s crust by their exposure to the atmosphere

2.Mention the three courses of a river with any two land forms associated to each course.

  • The course of a river is divided into

  • The Upper course – V shaped valleys, gorges
  • The middle course – Alluvial fans, flood plains
  • The lower course – Delta and Estuary.

3.Define Wind.

  • When air blows horizontally at or near the earth’s surface is called wind

4.What do you mean by a hanging valley?

  • These are vallys eroded by tributary glacier and that hangs over the main valley

5.What are the depositional landforms of wind?

  • Sand dunes
  • Barchans
  • Loess

Part – C

III. Write in detail:

1.Define weathering and classify it.

Weathering is the disintegration and decomposition of materials of the earth’s crust by their

exposure to atmosphere. There are three types of weathering,

(a) Physical weathering, (b) Chemical weathering (c) Biological weathering

  • Physical weathering: It is the breakdown of rocks without changing their chemical composition, through the action of physical forces. The constant freezing and thawing of rocks during the night and day leads to the expansion and contraction of rocks. Cracks are formed and disintegration occurs eventually. Exfoliation, block disintegration, granular disintegration etc., are the different types of weathering.
  • Chemical weathering: Disintegration and decomposition of rocks due to chemical reactions is called Chemical Weathering. This is predominantly high in the hot and humid regions such as the equatorial, tropical and sub tropical zones. Chemical weathering takes place through the processes of oxidation, carbonation, solution, and hydfation. The agents of Chemical weathering are Oxygen, Carbon-dioxide and Hydrogen.

  • Biological weathering: Biological weathering occurs due to the penetration and expansion of plant roots, earthworms, burrowing animals (rabbits, rats) and some human activities.

2.Explain depositional landforms of waves.

Answer : (coming soon)

Part – D

IV. Activity

See the picture below and fix the names of the missing landforms in

the appropriate place

  • 1) Interlocking Spurs
  • 2) Gorge
  • 3) Waterfall

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