Which of the following molecules contains one pair of non-bonding electrons?

Explain why $PCl_5$ is trigonal bipyramidal whereas $IF_5$ is square pyramidal.

Provide the structure of the $SO_{2}$ molecule and calculate the formal charge on each atom.

Identify the linear molecule from the following.

Assertion : All $F-S-F$ angles in $SF_4$ are greater than $90^\circ$ but less than $180^\circ$.
Reason : The lone pair-bond pair repulsion is weaker than bond pair-bond pair repulsion.

Which of the following orders cannot be explained by back bonding?