Question

A silver article turns black when kept in the open for a few days due to the formation of :

• A. ${\mathrm{H}}_2\mathrm{S}$
• B. $\mathrm{AgS}$
• C. ${\mathrm{AgSO}}_4$
• D. ${\mathrm{Ag}}_2\mathrm{S}$

Answer 1

The correct option is D

${\mathrm{Ag}}_2\mathrm{S}$

The correct option is (D):

Explanation for the correct answer:

${\mathrm{Ag}}_2\mathrm{S}$

1. When placed in air the Silver object turns black.
2. This is due to the the presence of Hydrogen sulfide(${\mathrm{H}}_2\mathrm{S}$) in the air, the Silver object reacts with the Hydrogen sulfide present in the air.
3. This whole process is actually known as corrosion which is basically the degradation or the destruction of the article when present in the excess moisture and air.
4. In the case of Silver element, corrosion is known as Silver tarnishing.
5. And so after this corrosion, the black substance formed is known as Silver sulfide.
6. Reaction: $\underset{\mathrm{Silver}}{2\mathrm{Ag}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}\mathrm{sulfide}}{{\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)}\to \underset{\mathrm{Silver}\mathrm{sulfide}}{{\mathrm{Ag}}_2\mathrm{S}\left(\mathrm{s}\right)}+\underset{\mathrm{Hydrogen}}{{\mathrm{H}}_2\left(\mathrm{g}\right)}$.

Therefore, the correct option is (D): ${\mathrm{Ag}}_2\mathrm{S}$.