2 mL each of concentrated HCl, HNO 3 and a mixture of concentrated HCl and concentrated HNO 3   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) Al

(B) Au

(C) Cu

(D) Pt



3:1 solution of HCl and HNO 3 is called Aqua regia and it is able to dissolve gold.

aqua regia 3 1 HCl to HNO3 - Teachoo.png

So, the correct option is (b) Au

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo