Question

Aqua regia is used for dissolving noble metals (Au, Pt, etc.). The gas evolved in this process is ______.

Options

• N₂

• NO

• N₂O₅

• N₂O₃

Answer 1

Aqua regia is used for dissolving noble metals (Au, Pt, etc.). The gas evolved in this process is NO.

Explanation:

Aqua regia dissolves noble metals like gold and platinum by forming complex chlorides. During this process, nitric acid reacts with hydrochloric acid, producing nitrosyl chloride (NOCl), which releases nitric oxide (NO) gas as a byproduct. Hence, the gas evolved is nitric oxide (NO). So, the gas evolved in aqua regia dissolving noble metals is NO (nitric oxide).