Question

Which is/are not correct variation of indicated properties in $N{H}_2^{-},N{H}_3$ and $N{H}_4^{+}$

• A. $N{H}_2^{-}<N{H}_3<N{H}_4^{+},(H-N-H)$ bond angle
• B. $N{H}_2^{-}<N{H}_3<N{H}_4^{+}$ lone pairs on $N$ - atom
• C. $N{H}_2^{-}<N{H}_3<N{H}_4^{+}(N-H)$ bond length
• D. $N{H}_2^{-}<N{H}_3<N{H}_4^{+}$ number of $s$ and $p$ - orbitals used in hybridisation

Answer 1

Answer: (B), (C), (D)

$N{H}_2^{-}<N{H}_3<N{H}_4^{+}$ number of $s$ and $p$ - orbitals used in hybridisation

a) Bond angle is maximum in $N{H}_4^{+}$ due to absence of any lone pair. So, (a) is correct.

b) Number of lone pair maximum in $N{H}_2^{-}$ thus (b) is incorrect.

c) As the number of lone pair increases, p-character in the NH bond increases and hence NH bond length increases. Hence the correct order of bond length,
$N{H}_2^{-}>N{H}_3>N{H}_4^{+}(N-H)$ bond length
hence c is incorrect.


d)All the three species are $s{p}^3$ hybridized and hence d is incorrect