Question

White ppt of A on reaction with ${aqNH}_3$ are blackened. Select correct statement about A.

• A. A is also called calomel
• B. A reacts with ${aqNH}_3$ forming ${HgNH}_{2}Cl$
• C. A changes to grey on reaction with ${SnCl}_2$
• D. All of the above are correct statements

Answer 1

The correct option is D All of the above are correct statements

White ppt of A is $\left(H{g}_{2}C{l}_2\right)$ It is a part of calomel electrode. It is water insoluble.

It reacts with ammonia to form $\left({HgNH}_{2}Cl+Hg\right)$. It is black in colour.

$H{g}_{2}C{l}_2+2N{H}_{4}OH\to H_{2}N-Hg-Cl+\underset{black}{Hg\downarrow }+N{H}_{4}Cl+2H_{2}O$.

A changes to grey on reaction with ${SnCl}_2$

$H{g}_{2}C{l}_2+SnC{l}_2\to 2Hg\downarrow +SnC{l}_4$

All the given statements are correct.