In solid state,$PCl_5$ is a/an

The number of $\sigma$ and $\pi$ bonds in $O_3$ molecule is:

The decreasing order of bond dissociation energies of $C-C$, $C-H$, and $H-H$ bonds is:

Which of the following sets are correctly matched?

Molecule	Number of lone pairs of electrons on central atom	Hybridization
$I. PCl_3$	$1$	$sp^3$
$II. SO_2$	$1$	$sp^2$
$III. SF_4$	$1$	$sp^3d$
$IV. ClF_3$	$2$	$sp^3d$

The $B-F$ bond dissociation energy in $BF_3$ is $646 \, kJ \, mol^{-1}$,whereas the $C-F$ bond dissociation energy in $CF_4$ is $515 \, kJ \, mol^{-1}$. Which of the following is the correct reason for the $B-F$ bond dissociation energy being higher than the $C-F$ bond dissociation energy?

The formation of $PH_4^+$ is difficult compared to $NH_4^+$ because