Which of the following is not applicable to metallic bonding?

Which of the following is not correctly matched?

Suggest the most important type of intermolecular attractive interaction in the following pairs.
$(i)$ $n$-hexane and $n$-octane
$(ii)$ $I_{2}$ and $CCl_{4}$
$(iii)$ $NaClO_{4}$ and water
$(iv)$ methanol and acetone
$(v)$ acetonitrile $(CH_{3}CN)$ and acetone $(C_{3}H_{6}O)$

The structures of beryllium chloride $(BeCl_2)$ in the solid state and vapour phase,respectively,are

The stability of an ionic crystal principally depends on:

The ionic compound $BaSO_4$ is insoluble in water due to