Give reason to explain why `ClF_(3)` exists but `FCl_(3)` does not exist.

Explanation

Reasons are : (i) Cl has vacant d-orbitals and hence can show an oxidation state of +3 but F has no d-orbitals, therefore, it cannot show positive oxidation states. Further, since F can show only -1 oxidation state, therefore, it can form only ClF 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.