When conc. H₂SO₄ is added to dry KNO₃, brown fumes are evolved. These fumes are of

Options

(a) SO₂
(b) SO₃
(c) NO
(d) NO₂

Correct Answer:

NO₂

Explanation:

When heated with conc. H₂SO₄ potassium nitrate undergoes double decomposition reaction forming free nitric acid. Some of the nitric acid gets decomposed to give brown fumes of nitrogen dioxide. KNO₃ + H₂SO₄ → KHSO₄ + HNO₃. 4HNO₃ → 4NO₂ + 2H₂O + O₂.