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JAMB Chemistry 1978 Question 7

Question 7

Separation of Mixtures

A small quantity of solid ammonium chloride (NH4Cl) was heated gently in a test tube, the solid gradually disappeared to produce a mixture of two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone

  1. A.distillation
  2. B.sublimation
  3. C.precipitation
  4. D.evaporation
  5. E.decomposition.
Show the answer and explanation

Answer: B (sublimation)

Explanation

The solid turns to vapour on heating and the solid re-forms on the cool part of the tube without passing through a liquid, which is sublimation.