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MCQ practice · SSC Chemistry Board questions · Chapter 11: Mineral Resources: Fossils

Barishal Board 2023

Ethanol (A) -(K₂Cr₂O₇, H₂SO₄)→ 'X' -(K₂Cr₂O₇, H₂SO₄)→ 'Y'. For 'A', 'X', 'Y':

  1. i. a 40% aqueous solution of 'X' is used to keep dead animals from rotting
  2. ii. a 4%-10% aqueous solution of 'Y' is used as a food preservative
  3. iii. a 96% aqueous solution of A is rectified spirit

Think it through first, then pick an option.

  1. a i and ii
  2. b i and iii
  3. c ii and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: c ii and iii

Y's 4-10% solution (vinegar) preserves food, and A's roughly 96% solution (95.6% in the book) is rectified spirit.

Why the other options are wrong

  • a i and ii: i is wrong: X is ethanal; the 40% solution for preserving bodies (formalin) is methanal's; the answer is ii and iii.
  • b i and iii: i is wrong: formalin is methanal, not X (ethanal), and ii is left out; the answer is ii and iii.
  • d i, ii and iii: i is wrong: formalin is methanal, not ethanal; so not all three.