(a), (b) and (d) are correct options.

(a) ${\mathrm{I}}^{\ominus }>{\mathrm{Br}}^{\ominus }>{\mathrm{Cl}}^{\ominus }>\mathrm{F}$ (Polarisability).

According to Fajan's rule, large anion is more polarisable.

(b) ${\mathrm{Li}}^{\oplus }>{\mathrm{Na}}^{\oplus }>{\mathrm{K}}^{\oplus }>{\mathrm{Rb}}^{\oplus }$ (Polarisation power).

According to Fajan's rule, small cation is more polarisable.

(c) Wrong.

      Boiling point order is

(d) Both ${{\mathrm{H}}_2}^{\ominus }\text{ and }{\mathrm{H}}_2^{\oplus }$ have same bond order of 0.5.
     ${\mathrm{H}}_2^{\oplus }$ is more stable than ${{\mathrm{H}}_2}^{\ominus }$, since ${\mathrm{H}}_2^{\oplus }$contains
     one e^- in bonding orbitals whereas ${{\mathrm{H}}_2}^{\ominus }$ contains
     one e^- in antibonding orbitals.