Question

Select the incorrect statement about $N_2{F}_4$ and $N_2{H}_4$ :
(I) In $N_2{F}_4,$ $d-$ orbitals are contracted by electronegative fluorine atoms, but $d-$ orbital contraction is not possible by $H-$ atom in $N_2{H}_4$
(II) The $N-N$ bond energy in $N_2{F}_4$ is more than $N-N$ bond energy in $N_2{H}_4$
(III) The $N-N$ bond length in $N_2{F}_4$ is more than that in $N_2{H}_4$
(IV) The $N-N$ bond length in $N_2{F}_4$ is less than that in $N_2{H}_4$
Choose the correct code-

• A. I, II and III
• B. I and III
• C. II and IV
• D. II and III

Answer 1

Answer: (B)

In $N_2{F}_4,N-N$ bond has more s-character hence bond length decreases.

While in $N_2{H}_4,N-N$ bond has less s-character (i.e., more p-character), hence bond lengths is more.