Answer: (b) Au
Solution C is a mixture of concentrated HCl and concentrated HNO3 which is called aqua regia. Aqua Regia dissolves gold.
Aqua regia is a yellow-orange or sometimes red colour fuming liquid. Aqua regia is a mixture of nitric acid and hydrochloric acid, at a molar ratio of 1:3 optimally.
Use of Aqua regia
Some uses of aqua regia are listed below.
- It can dissolve noble metals such as gold and platinum but not all metals.
Aqua regia is mainly used for the manufacture of chloroauric acid.
It is used as an electrolyte in the Wohlwill process to refine gold of the highest quality (99.999%).