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GeographyEasyAsked in: CDS · CDS-II 2025, GK

Which of the following statements with reference to Water Vapour in the atmosphere is/are correct ? 1. It has a role to play in the stability and instability in the air. 2. It acts like a blanket allowing the earth to neither become too cold nor too hot. Select the answer using the code given below :

  1. A.1 only
  2. B.2 only
  3. C.Both 1 and 2
  4. D.Neither 1 nor 2

Correct answer

C. Both 1 and 2

Explanation

The correct answer is C, Both 1 and 2. Both statements are true, and UPSC's official key also gives C.

Water vapour is a variable gas, from almost nil in cold deserts to about 4 percent of the air by volume in the warm, humid tropics. It absorbs part of the incoming solar radiation and much of the heat given out by the earth, so it acts like a blanket, keeping the earth from becoming too hot by day or too cold by night. When vapour condenses it releases latent heat, which warms the rising air and makes it more unstable, driving thunderstorms and cyclones; dry air, by contrast, tends to be stable. So vapour shapes both temperature and the stability of the air.

A is wrong because it leaves out the true blanket effect. B is wrong because it leaves out the true role in stability. D is wrong because both statements are correct.

Exam tip: water vapour is the most variable gas, up to 4 percent by volume; it absorbs heat and releases latent heat on condensation.

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.