What happens when ferrous sulphate crystals are heated?
(a) A gas having the smell of burning sulphur is evolved
(b) No gas is evolved
(c) Brown coloured gas is evolved
(d) Colourless and odourless gas is evolved.

Correct Answer: (a) A gas having the smell of burning sulphur is evolved

Explanation: The green colour of ferrous sulphate crystals changes to brownish-black ferric oxide and smell of burning sulphur is evolved due to SO₂ and SO₃.