2 mL each of conc. HCl, `HNO_(3)` and a mixture of conc. HCl and conc. `HNO_(3)` in the ratio of3 : 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. The metal could be 

Options

A. Al
B. Au
C. Cu
D. Pt

Answer

B

Explanation

Aqua regia is a mixture of concentrated hydrochloric acid and concentrated nitric acid in the ration of 3 : 1. It can dissolve gold, even though neither of these acids can do so alone. Aqua regia is a highly corrosive, fuming liquid. It is one of the few reagents that is able to dissolve gold and platinum.