The compounds of type ECl3  where E=B,P,As(or) Bi the angles Cl−E−Cl for different E are in the order.

1) In BCl3 , Boron undergoes sp2 Hybridization. So the bond angle is 120∘C2) In PCl3, AsCl3,BiCl3 ,  &  the central atom undergoes  sp3  and one lone pair. Hence the bond angles<109∘28'3) When the hybridization and the number of lone pairs are same, then as the size of the central atom increases, bond angle decreases.