Correct Answer - D
On account of high electronegativity, high ionization enthalpy, and great polarizing power be `Be^(2+)` ion, anhydrous compounds of Be are covalent. Only hydrated salts of `Be^(2+)` ion such as `[Be(H_(2)O)_(4)]CI_(2)` are known, Mg also shows some tendency for covalency. All other elements form compounds which are predominantly ionic, but they are less ionic than the compounds of corresponding alkali metals because of higher ionization enthalpies and greater polarizing power of divalent metal ions.
