Vanadium chloride is prepared from the vanadium penta fluoride with excess boron trichloride. VF5+10BCl3⟶[VCl5]2+10BF2Cl VF5 have very higher bond enthalpy. VCl5 does not exist due to stearic hinderance, but its exist as dimer in solid state. So, Assertion (A) is true. The ability of fluorine to stabilise higher oxidation states is due to it's higher bond enthalpy or lattice energy. Fluorine is most electronegative which hold high negative charge stability and the compound is stabilised. So, Reason (R) is also true. Hence, A and R are true and R is the correct explanation of A.