Identify the correct option.

Which of the following is paramagnetic?

Select the incorrect statement about $N_2F_4$ and $N_2H_4$ :
$(I)$ In $N_2F_4$,$d$-orbitals are contracted by electronegative fluorine atoms,but $d$-orbital contraction is not possible by $H$ atoms in $N_2H_4$.
$(II)$ The $N-N$ bond energy in $N_2F_4$ is more than the $N-N$ bond energy in $N_2H_4$.
$(III)$ The $N-N$ bond length in $N_2F_4$ is more than that in $N_2H_4$.
$(IV)$ The $N-N$ bond length in $N_2F_4$ is less than that in $N_2H_4$.
Choose the correct code:

Identify the statement$(s)$ which is(are) not correct from the following:
$a)$ $NH_3$ and $H_3O^+$ are isostructural
$b)$ $ClF_3$ has $T$-shape
$c)$ $O_2$ molecule is paramagnetic
$d)$ Bond order of $N_2^+$ is more than $N_2$

The type of molecular forces of attraction present in the following compound is

The correct order in which the $O-O$ bond length increases in the following is