According to the vsepr model, the progressive decrease in the bond angles in the series of molecules ch₄, nh₃, and h₂o is best accounted for by the

lone pair-bond pair repulsion is best accounted for decrease in bond angle

Explanation:

Bond angle in each compounds depends on presence of lone pair on central atom.

In , there is no lone pair on C atom. So, no lone pair-bond pair repulsion is present here. Hence is

In , there is one lone pair on N atom. So, one lone pair-bond pair repulsion is present here. Hence is

In , there are two lone pairs on O atom. So, two lone pair-bond pair repulsion are present here. Hence is

So, lone pair-bond pair repulsion is best accounted for decrease in bond angle