Explain the following:
(a) Lithium iodide is more covalent than lithium fluoride
(b) Lattice enthalpy of LiF is maximum among all the alkali metal halides.

Explanation

According to Fazan.s rule, `Li^(+)` ion can polarise `I^(-)` ion more than the `F^(-)`ion due to bi size of the anion. Thus `Lil^(-)` has more covalent character than Lif.
(b) Smaller the size (internuclear distance), more is the value of lattice enthalpy since internuclear distance is expected to be least in the LiF.