Compare the alkali metals and alkaline earth metals with respect to (a) ionisation enthalpy, (b) basicity of oxides and (c ) solubility of hydroxides.

Explanation

a.`IE`:`IE_(1)` of group `2`elements are greater than those of corresponding group `1` elements, due to higher effective nuclear charge `(Z_(eff))` of group `2` elements.
b. Basicity of oxides: Their oxides dissolve in water to form their respective hydroxides which are strong bases. Sine the `IE_(1)` of the `Ist` group is lower or the electropositive character of `Ist` group metals is higher than that of the corresponding `2nd` group metals, therefore `(M-OH)` bond is `Ist` group metals is ionised more easily `(MOHtoM^(o+)+overset(ө)(O)H)` than `2nd` group metals. Hence, alkali metal oxides are more basic than the corresponding alkaline earth metal oxides.
c. Solubility ofhydroxides: Because of high charge density, the lattice enthalpies of `2nd` group metals are much higher than those of `ist` group metals and hence the solubility of alkali metal hydroxides is much higher than that of alkaline earth metal hydroxides. However, the solubility of the hydroxides of both alkali and alkaline earth metals increase down the group due to larger decrease in their enthalpies as compound to their hydration enthalpies.