`CIF_(3)` exists but `FCl_(3)` does not. Why ?

Answer

Reason are:(i)`Cl` has vacant d-orbitals and hence can show positive oxidation states.Further, since `F` can show only `-1` oxidation state, therefore, it can form only `CIF` and not `FCl_(3)`.
(ii)Because of bigger size, `Cl` can accommodate three small F atoms around it while F being smaller cannot accommodate three bigger sized Cl atoms around it.