Find the total number of molecules which contain axial bond length greater than equatorial bond length? ${\mathrm{PCl}}_5,{\mathrm{SF}}_4,{\mathrm{SF}}_6,{\mathrm{CCl}}_4,{\mathrm{NO}}_3^{-},{\mathrm{SO}}_4^{2-}$

${\mathrm{PCl}}_5$ Phosphorus pentachloride and  ${\mathrm{SF}}_4$ Sulphur tetrafluoride contain axial bond length greater than equatorial bond length.

Because of the greater repulsion from equatorial bonds, the axial bonds are longer than equatorial ones. Axial bonds are therefore closer to equatorial bonds, which leads to higher repulsion and an increase in bond length.

Thus, correct answer is 2.