State your observation when the following are exposed to the atmosphere:

(a) Washing soda crystals

(b) Iron (III) chloride salts.

Give reasons for the following:

(a) Sodium hydrogen sulphate is not an acid, but it dissolves in water to give hydrogen ions according to the equation

NaHSO₄ ⇌ H⁺ + Na⁺ + SO₄^2-

(b) Anhydrous calcium chloride is used in a desiccator.

Distinguish between drying and dehydrating agent.

State whether a sample of each of the following would increase or decrease in mass if exposed to air.

(a) Solid NaOH

(b) Solid CaCl₂

(c) Solid Na₂CO₃.10H₂O

(d) Conc. Sulphuric acid

(e) Iron (III) Chloride