JAMB Chemistry 1986 Question 24

Question 24

Water

Which of the following contains an efflorescent, a deliquescent and a hygroscopic substance respectively?

A.Na₂SO₄, concentrated H₂SO₄, CaCl₂
B.Na₂CO₃.H₂O, FeSO₄.7H₂O, concentrated H₂SO₄
C.Na₂CO₃.10H₂O, FeCl₃, concentrated H₂SO₄
D.Concentrated H₂SO₄, FeSO₄.7H₂O, MgCl₂.

Show the answer and explanation

Answer: C (Na₂CO₃.10H₂O, FeCl₃, concentrated H₂SO₄)

Explanation

Washing soda (Na₂CO₃.10H₂O) loses water to the air (efflorescent), FeCl₃ absorbs water until it dissolves (deliquescent), and concentrated H₂SO₄ absorbs water without dissolving into a solution of a solid (hygroscopic).