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NDA 2 2025 GAT, question 113

Topic: Geography

Q113

Consider the following pairs with reference to sedimentary rocks and the process of their formation :

Sedimentary Rock Process of Formation
1. Chert Chemically formed
2. Geyserite Organically formed
3. Shale Mechanically formed

Which of the pairs given above is/are correctly matched ?

  1. (a) 1 only
  2. (b) 1 and 2 only
  3. (c) 2 and 3 only
  4. (d) 1, 2 and 3Correct answer

Solution.

Answer: (d) 1, 2 and 3

  1. Chert is a chemically formed sedimentary rock.
  2. Geyserite is listed in NCERT among organically formed rocks.
  3. Shale is mechanically formed, from compacted clay and silt.

Trap: Geologists usually class geyserite as a chemical deposit from hot springs; the key follows the NCERT grouping, where all three pairs match.