2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl

• GC Metals Non-Metals

2 mL each of concentrated HCl, HNO₃ and a mixture of concentrated HCl and concentrated HNO₃ in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be

1. Al
2. Au
3. Cu
4. Pt

Answer

A mixture of conc. HCI and conc. HNO₃ in the ratio of 3 : 1 forms aqua-regia which can dissolve gold (Au) and platinum (Pt).

The correct option is D.