The compounds of type ECl3 where E=B,P,AS(or) Bi the angles Cl-E-Cl for different E are in the order.
B>P=As=Bi
B>P>As>Bi
B<P=As=Bi
B<P<As<Bi
1) In BCl3 Boron undergoes sp2 Hybridization 120∘
2) In PCl3,AsCl3&BiCl3 the central atom undergoes sp3 and one lone pair.
Hence the bond angles< 109°281