Which of the following compounds is used for the preparation of quicklime?

Identify correct statements from the following:
$i$. Beryllium oxide is an amphoteric oxide.
$ii$. Group $II$ elements dissolve in liquid ammonia to form deep blue-black solutions.
$iii$. The hydration enthalpy of group $II$ ions decreases from $Be^{2+}$ to $Ba^{2+}$.

Select the incorrect order of solubility.

The pair of amphoteric hydroxides is

Assertion : Barium is not required for normal biological function in humans.
Reason : Barium does not show variable oxidation states.

Which elements are considered as alkaline earth metals? Give a brief description of them.