Question

Assertion $\left(A\right):$ The ionization of hydrogen sulfide in water is low in the presence of hydrochloric acid.

Reason $I:$ Hydrogen sulphide is a weak acid

• A. Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$
• B. Both $A$ and $R$ are true and $R$ is the correct explanation of $A.$
• C. $A$ is true but $R$ is false.
• D. $A$ is false but $R$ is true.

Answer 1

The correct option is A

Both $A$ and $R$ are true but $R$ is not the correct explanation of $A.$

Analyzing the assertion

The ionization of $H_{2}S$ in water is low in the presence of $HCl.$ Yes, it is correct statement. It occurs because of common Ion effect.

Analyzing the reason

$H_{2}S$ is weak acid,

Yes, it is correct statement too.

But this is not a correct explanation of given $A$ because the low ionization of $H_{2}S$ (weak acid) in presence of $HCl$ (strong acid) is due to the presence of common ion effect because of $H^{+}$ ion.

$H-Cl\to H^{+}+C{l}^{-}$

$H_{2}S\rightleftharpoons H^{+}+H{S}^{-}$
Hence, Both assertion and reason are true but reason is not the correct explanation of assertion

$\therefore$ Correct answer is option $\left(B\right).$