Question

Assertion :$N_2{H}_4$ is a weaker base than $N{H}_3$ Reason: Its behaviour is bifunctional

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

Hydrazine is essentially a substitution product of ammonia where hydrogen has been replaced by $-N{H}_2$. It is a weaker base than ammonia because the more electronegative group $-N{H}_2$ has the - I effect on the lone pair of electron of the neighbouring nitrogen, making it less basic for protonation.

$N_2{H}_4+H_{2}O\to [N_2{H}_5{]}^{+}+[OH{]}^{-}$ $K_{25}=8.5\times {10}^{-7}$

$[N_2{H}_5{]}^{+}+H_{2}O\to [N_2{H}_6{]}^{2+}+[OH{]}^{-}$ $K_{25}=8.9\times {10}^{-16}$