Question

Noble metals like gold and platinum are soluble in which of the following mixtures?

• A. $1 : 1$ mixture of conc. $HNO_3$ and conc. $H_2SO_4$
• B. $1 : 3$ mixture of conc. $HCl$ and conc. $HNO_3$
• C. $1 : 3$ mixture of conc. $HNO_3$ and conc. $HCl$
• D. $1 : 3$ mixture of conc. $H_2SO_4$ and conc. $HCl$

Answer 1

Answer: (C)

$1 : 3$ mixture of conc. $HNO_3$ and conc. $HCl$

Answer 2

Nubel metal such as gold and platinum are soluble in aqua-regia which is a mixture of nitric acid and hydrochloric acid in molar ratio of $1: 3$. i.e. $3 HCl +1 HNO _{3}=$ aqua-regia