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GeographyEasyAsked in: NDA · NDA-II 2018, GAT

Which one of the following is not a process of chemical weathering?

  1. A.Solution
  2. B.Carbonation
  3. C.Oxidation
  4. D.Exfoliation

Correct answer

D. Exfoliation

Explanation

The correct answer is D, Exfoliation. Exfoliation is a process of physical (mechanical) weathering, in which outer layers of rock peel off like the skin of an onion, with no change in the rock's chemical make-up.

In hot deserts, rock surfaces heat up strongly by day and cool sharply at night. The outer layers expand and contract more than the inside, so they crack and peel away in curved sheets; the release of pressure on rocks once buried deep also helps. The result is rounded rock domes, and the process is also called onion weathering. Chemical weathering, by contrast, changes the minerals themselves through reactions with water, oxygen and acids, and it is most active in hot, wet climates.

A is wrong because solution, in which minerals such as rock salt or gypsum dissolve in water, is a chemical process. B is wrong because carbonation, the reaction of carbonic acid in rainwater with limestone, is chemical. C is wrong because oxidation, the reaction of iron in minerals with oxygen, is chemical.

Exam tip: chemical weathering, solution, carbonation, oxidation, hydration, hydrolysis; physical weathering, exfoliation, frost action, salt crystal growth.

Practice Questions

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Q2.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements is/are correct? 1. Himalayan rivers have their origin in the snow-covered areas, hence are dry in winter season. 2. Rivers of the Peninsular Plateau have reached maturity. 3. Himalayan rivers depict all the three stages of normal cycle of erosion. Select the correct answer using the code given below.

  1. A.2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: C. 2 and 3 only

Himalayan rivers are perennial, so statement 1 is wrong, while statements 2 and 3 are correct. Himalayan rivers such as the Ganga, Indus and Brahmaputra rise from glaciers and snowfields and also get monsoon rain, so they flow all year round, including in winter.

Q3.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following statements related to latitude are true? 1. Rainfall, temperature and vegetation vary with latitude. 2. The difference between the longest day and the shortest day increases with latitude. 3. Indira Point is located approximately at 6°45' N latitude. Select the correct answer using the code given below.

  1. A.1 and 2 only
  2. B.1 and 3 only
  3. C.2 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: D. 1, 2 and 3

All three statements about latitude are true. Latitude decides how directly the Sun's rays strike a place, so temperature, rainfall and the type of vegetation change from the equator towards the poles, from hot, wet rainforests to cold tundra.

Q4.GeographyAsked in: CDS · CDS-II 2017, GKMedium

Which of the following lakes is/are situated in Ladakh? 1. Tso Kar 2. Pangong Tso 3. Tsomgo 4. Tso Moriri Select the correct answer using the code given below.

  1. A.1 only
  2. B.2 and 3
  3. C.1, 2 and 4
  4. D.2 and 4 only
Show answer
Correct answer: C. 1, 2 and 4

Tso Kar, Pangong Tso and Tso Moriri are high-altitude lakes of Ladakh, while Tsomgo lies in Sikkim. Pangong Tso, at about 4,350 metres, is a long, narrow lake that stretches from Ladakh into Tibet, and most of its length lies on the Chinese side.