Identify the correct statement from the following.

A. Among alkali metal ions, $\mathrm{Li}^{+}$has highest hydration enthalpy.

B. Boiling point of alkali metals increases from Li to Cs .

C. Density of K is less than that of Na and Rb .

D. Li has strong tendency to form superoxide.

The correct answer is

Consider the following

Statement - I : Both $\mathrm{BeSO}_4$ and $\mathrm{MgSO}_4$ are readily soluble in water.

Statement - II : Among the nitrates of alkaline earth metals, only $\mathrm{Be}\left(\mathrm{NO}_3\right)_2$ on strong heating gives its oxide, $\mathrm{NO}_2$ and $\mathrm{O}_2$.

The correct answer is

Which chloride does not exist as hydrate?

The correct order of density of $\mathrm{Be}, \mathrm{Mg}, \mathrm{Ca}, \mathrm{Sr}$ is