Which of the following behaves as a Lewis acid?

Calculate $x + y + z$ for $H_3PO_3$ acid,where $x$ is the number of lone pairs,$y$ is the number of $\sigma$ bonds,and $z$ is the number of $\pi$ bonds.

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?

Which of the following odd electron species is planar?

The number of $Cl=O$ bonds in perchloric acid is:

In which of the following pairs of species is the bond length as well as the bond energy of the $I^{st}$ species less than the $II^{nd}$ species?