What is the bond angle around an atom that undergoes $sp^2$ hybridization?

The valency of carbon is $4$. On what principle can it be explained in a better way?

Identify the correct match:

Column $I$ (Molecule/ion)	Column $II$ (Hybridisation)
$A$. $H_3O^{+}$	$P$. $sp$
$B$. $NH_2^{-}$	$Q$. $sp^2$
$C$. $NO_3^{-}$	$R$. $sp^3$
$D$. $ClF_3$	$S$. $sp^3d$

What is the type of hybridization of $Xe$ in $XeF_2$?

Assertion : Among the carbon allotropes,diamond is an insulator,whereas,graphite is a good conductor of electricity.
Reason : Hybridization of carbon in diamond and graphite are $sp^3$ and $sp^2$,respectively.

The hybridisation of $S$ in $SF_{4}$ is