Question

# 2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl and concentrated HNO3 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

$\mathrm{Al}$

No worries! We‘ve got your back. Try BYJU‘S free classes today!
B

$\mathrm{Au}$

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C

$\mathrm{Cu}$

No worries! We‘ve got your back. Try BYJU‘S free classes today!
D

$\mathrm{Pt}$

No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

## The correct option is B $\mathrm{Au}$Explanation for Correct option Option (B) $\mathrm{Au}$Aqua regiaSolution C is a mixture of concentrated $\mathrm{HCl}$and concentrated ${\mathrm{HNO}}_{3}$which is called aqua regia. Aqua Regia dissolves gold.Aqua regia is a yellow-orange or sometimes red color fuming liquid. Aqua regia is a mixture of nitric acid and hydrochloric acid, at a molar ratio of $1:3$optimally.Use of Aqua regiaIt 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 $\left(99.999%\right)$.Explanation for incorrect option Option (A) $\mathrm{Al}$Since aluminum is weakly oxidized to its particular ionic form.Thus it will not behave suitably in aqua regia.This option is incorrect.Option (C) $\mathrm{Cu}$Copper is a weak metal.Thus it is oxidized with difficulty.The option is incorrect.Option (D) $\mathrm{Pt}$Platinum doesn't oxidize easily.Thus this option is incorrect.Hence the metal is Aurum (Gold).

Suggest Corrections
0
Explore more