Question

Q.20.2 ml each of concentrated HCI, HNO, and a mixture of concentrated
HCl and concentrated HNO 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 *
A. AI
B. Au
C. Cu D. All the above​

Answer 1

A mixture of three parts of concentrated hydrochloric acid and one part of concentrated nitric acid(Aqua regia - 3:1 ratio) is capable of dissolving gold. ... Hence, the metal in test tube C must be gold (Au). The correct option is (B).