Which of the following molecules contains the maximum S-O bond length? : `SO_2`, `SO_3` , `SO_4^(2-)`, `SO_3^(2-)`

Options

A. `SO_2`
B. `SO_3`
C. `SO_4^(2-)`
D. `SO_3^(2-)`

Answer

D

Explanation

In `SO_2` and `SO_3`, all the bonds are double bonds. In `SO_3^(2-)` and `SO_4^(2-)` also, all the bonds are of the same type due to resonance. But in `SO_3^(-2)` charge is delocalized over three atoms whereas it is delocalized over four atoms in `SO_4^(2-)`, So, bond order is lowest for so. Thus, `SO_3^(2-)` -contains the maximum S-O bond length.