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GeographyMediumAsked in: NDA · NDA-II 2026, GAT

Consider the following statements with regard to igneous rocks : I. These rocks cannot be changed into metamorphic rocks. II. When molten material is cooled slowly at great depths, mineral grains tend to be very small. III. These rocks are known as primary rocks. Which of the statements given above is/are correct ?

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

Correct answer

B. III only

Explanation

The correct answer is B, III only. Igneous rocks are called primary rocks, but they can be changed into metamorphic rocks, and slow cooling gives large grains, not small ones.

Igneous rocks form when magma or lava cools and solidifies. Because every other rock type can ultimately be traced back to them, they are called primary rocks. The size of their grains depends on the rate of cooling: magma that cools slowly deep inside the crust, as in granite, grows large crystals, while lava that cools fast at the surface, as in basalt, gives fine grains or even glass. Under heat and pressure, igneous rocks recrystallise into metamorphic rocks; granite, for example, becomes gneiss.

Statement I is wrong because granite turning into gneiss shows that igneous rocks can become metamorphic. Statement II is wrong because slow cooling at great depth produces large grains. So A, C and D, which include I or II, are wrong.

Exam tip: slow cooling at depth gives coarse grains (granite); fast cooling at the surface gives fine grains (basalt).

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.