Which of the following repulsions is highest? (if considered at same angle)
The order of strength of repulsion betwen the electron pairs follow the order
lp−lp>lp−bp>bp−bp
Therefore the options with lone pair - lone interactions will have the highest repulsions.
Of options a) 1 lp - lp, 5 lp - bp and d)1 lp - lp, 5 bp - bp
Since lone pair - bond pair repulsions are stronger than bond pair - bond pair repulsions a) 1 lp - lp, 5 lp - bp will have the highest repulsions.