Question

A metal $M$ which is not affected by strong acids like conc.$H{NO}_3$, conc. $H_2{SO}_4$ and conc. solution of alkalies like $NaOH$ and $KOH$. It forms $M{Cl}_3$, which finds use for tanning in photography. The metal $M$ is:

• A. $Ag$
• B. $Hg$
• C. $Au$
• D. $Cu$

Answer 1

The correct option is C $Au$

Gold is not affected by strong acids like conc.$HN{O}_3$, conc. $H_{2}S{O}_4$ and conc. solution of alkalies like NaOH, KOH
It dissolves only in aqua regia or nascent chlorine.

$AuC{l}_3$ gives golden shade to the printed photograph. Hence, it is used for toning in photography.