Which of the following statements is true?

During the formation of a chemical bond,

Maximum bond angle is present in

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 $XeF_4$.

Considering ethene molecule,which of the following statements is/are correct?
$I$. $C-C$ bond is formed by overlapping of $sp^2-sp^2$ hybrid orbitals.
$II$. $C-H$ bond is formed by overlapping of $sp^2-s$ orbitals.
$III$. $p\pi-p\pi$ bond is present.
$IV$. $H-C-H$ bond angle is greater than $H-C-C$ bond angle.
$V$. Nodal plane of $\pi$ bond and molecular plane are same.

Which of the following species contains an equal number of $\sigma -$ and $\pi -$ bonds?