arramge in the increasing order of bond angle
NH3, NH4+, NH2-
The increasing order of bond angles is given as:
NH2- < NH3 < NH4+
Reason: NH4+ has tetrahedral shape with bond angle 109.5degree. NH3 has trigonal pyramidal shape and has one lone pair which pushes the bond closer. And NH2- has bent shape and there are two lone pairs present which pushes the bonds even closer than in NH3 molecule which makes the angle smaller.
NH2- < NH3 < NH4+
Reason: NH4+ has tetrahedral shape with bond angle 109.5degree. NH3 has trigonal pyramidal shape and has one lone pair which pushes the bond closer. And NH2- has bent shape and there are two lone pairs present which pushes the bonds even closer than in NH3 molecule which makes the angle smaller.