Question

Assertion: $H_{2}S$ is stronger acid than $P{H}_3$.
Reason: S is more electronegative than P, conjugate base $H{S}^{-}$ is more stable than $H_2{P}^{-}$.

• A. If both assertion and reason are true and reason is the correct explanation of assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of assertion.
• C. If assertion is true but reason is false.
• D. If both assertion and reason are false.

Answer 1

Answer: (A)

$H_2{S}_{(g)}+aq\to H{S}_{(aq)}^{-}+H_{(aq)}^{+}$
$P{H}_{3(g)}+aq\to H_2^{-}+H_{(aq)}^{+}$
As S is more electronegative than P, conjugate base $H{S}_6^{-}$ is more stable than $H_2{P}^{-}$. Hence, $H_{2}S$ is stronger acid than $P{H}_3$.