Passivity of iron is due to the formation of

Assertion : $PbI_4, BiCl_5, FeI_3, CuI_2$ do not exist. Reason : Higher oxidation states of metal ions are strong oxidising agents which give redox reactions with the iodide ion.

Write the chemical reactions of lanthanoids $(Ln)$ with the following:
$(1)$ With acid:
$2Ln + 6HCl \rightarrow 2LnCl_3 + 3H_2$
$(2)$ With halogens ($X_2$,where $X = F, Cl, Br, I$):
$2Ln + 3X_2 \rightarrow 2LnX_3$

$A$ transition metal exists in its highest oxidation state. It is expected to behave as

Explain the catalytic properties of transition metals.

Assertion $(A):$ $VF_5$ is stable while $VCl_5$ is not.
Reason $(R):$ Fluorine stabilizes the higher oxidation state due to its higher bond enthalpy.
The correct option among the following is