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GeographyHardAsked in: NDA · NDA-II 2025, GAT

Consider the following statements with reference to sea waves : 1. The height of waves is determined by wind speed, wind duration, and fetch 2. The energy of a wave is proportional to the square of its height 3. Waves retain most of their energy as they travel across the deep ocean Which of the statements given above is/are correct ?

  1. A.1 only
  2. B.1 and 2 only
  3. C.2 and 3 only
  4. D.1, 2 and 3

Correct answer

D. 1, 2 and 3

Explanation

The correct answer is D, 1, 2 and 3. All three statements describe how ocean waves form and travel.

Statement 1 is correct: wind-driven waves grow with the wind's speed, the length of time it blows and the fetch, the stretch of open water over which it blows. Statement 2 is correct: the energy carried by a wave is proportional to the square of its height, so a wave twice as high carries four times the energy, which is why storm waves are so destructive. Statement 3 is correct: in deep water a wave moves energy, not water, and the water particles only turn in circles, so little energy is lost; swells born in Southern Ocean storms can cross an entire ocean. Most of the energy is spent only when waves reach shallow water and break on the coast.

A is wrong because it leaves out statements 2 and 3. B is wrong because it leaves out statement 3. C is wrong because it leaves out statement 1, the basic rule of wave growth.

Exam tip: wave height grows with wind speed, duration and fetch; energy goes with the square of height.

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.