In which of the following molecules,all atoms are coplanar?

The correct statements from the following are:
$a$) The total number of sigma bonds present in benzene is $12$
$b$) $LiF$ is more covalent than $KF$
$c$) $SnCl_2$ is more covalent than $SnCl_4$

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:

The correct order as indicated in each option is

Which of the following statements is correct?

Arrange the bonds in order of increasing ionic character in the molecules: $LiF$,$K_2O$,$N_2$,$SO_2$,and $ClF_3$.