A black coloured solid which on reaction with dilute sulphuric acid forms a blue coloured solution is:
(a) Carbon
(b) Manganese [IV] oxide
(c) Lead [II] oxide
(d) Copper [II] oxide

Copper [II] oxide

Reason

Copper [II] oxide is black in colour and the following reaction takes place when it is treated with dilute sulphuric acid —

CuO + H₂SO₄ ⟶ CuSO₄ + H₂O

CuSO₄ is a blue coloured soln.