Which of the statements given below is incorrect?

Which of the following statements is incorrect?
$(i)$ $NaCl$,being an ionic compound,is a good conductor of electricity in the solid state.
$(ii)$ In canonical structures,there is no difference in the arrangement of atoms.
$(iii)$ Hybrid orbitals form stronger bonds than pure orbitals.
$(iv)$ $VSEPR$ theory can explain the square planar geometry of $XeF_4$.

Observe the following sets:

Label	Order	Property
$i.$	$NH_3 > H_2O > SO_2$	Bond angle
$ii.$	$H_2O > NH_3 > H_2S$	Dipole moment
$iii.$	$N_2 > O_2 > H_2$	Bond enthalpy
$iv.$	$NO^{+} > O_2 > O_2^{2-}$	Bond order

Which of the above sets are correctly matched?

Which of the following pairs are isoelectronic?

Incorrect statement regarding $N(SiH_3)_3$ is

The correct order of strength of $\pi-$ bond$(s)$ is:
$I$. $BO_3^{-3} < CO_3^{-2} < NO_3^{-}$
$II$. $ClO_4^{-} > SO_4^{-2} > PO_4^{-3}$
$III$. $BF_3 > BCl_3 > BBr_3$
$IV$. $AlCl_3 < BCl_3$