Question

Assertion: $S{{b}_{2}}{{S}_{3}}$ is not soluble in yellow ammonium sulfide.
Reason: The common ion effect due to ${{S}^{2-}}$ ions reduce solubility of $S{{b}_{2}}{{S}_{3}}$.
(a)- Both the assertion and the reason are correct and the reason is the correct explanation for the assertion.
(b)- Both the assertion and the reason are correct and the reason is not the correct explanation for the assertion.
(c)- The assertion is correct but the reason is incorrect.
(d)- Both the assertion and the reason are incorrect.

Answer 1

When the color of the ammonium sulfide changes from white to yellow the solubility will increase as the sulfur ion increases which will increase the common ion effect.

Complete step by step answer:
The given assertion says that the $S{{b}_{2}}{{S}_{3}}$ is not soluble in yellow ammonium sulfide but this is not true because when the color of the ammonium sulfide changes from white to yellow the solubility of $S{{b}_{2}}{{S}_{3}}$ increases. When the reaction between the $S{{b}_{2}}{{S}_{3}}$ and yellow ammonium sulfide will form thiosalts. The reaction is given below:
$S{{b}_{2}}{{S}_{3}}+3{{(N{{H}_{4}})}_{2}}S\to 2{{(N{{H}_{4}})}_{3}}Sb{{S}_{2}}$
- This is due to the fact that when the color changes from white to yellow the number of sulfur increases, therefore the ions of the sulfur atoms increases, i.e., ${{S}^{2-}}$ ions. So, as the amount of the sulfur ions increases the common ion effect also increases. Therefore, we can say that as the common ion effect increases the solubility will also increase. Hence the reason is also incorrect.
So, the correct answer is “Option D”.

Note: Generally the solubility of the solute will decrease due to the common ion effect but the common ion effect due to ${{S}^{2-}}$ ions increase the solubility of $S{{b}_{2}}{{S}_{3}}$ is an exception. Also as the atomic number increases the solubility increases.