Due to electronic repulsion between the lone pairs in unhybridised s and p orbitals , group 16 elements show decreasing tendency to be in +2 state down the group rather they tend to show more stability towards +4 and +6 states. Thus selenium stays in lower oxidation state and do not form dihalides.

Why does oxygen not form Dihalides?

SF. Isa gas. SeFeAiiqu'd mese fluorides have sp'd hybridisation and thus, have structures in Which one of the equator. ... This geometry , All elements except oxyqen form dichlorides and di6an&s dihalides are forrned by sp hybridisation and thus. have sa-•acture.

Can Oxygen form Dihalides?

These dihalides are formed by sp hybridisation and thus, have tetrahedral structure.