Epsom salt is a hydrate of which of the following?

The substance not likely to contain $CaCO_3$ is

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 $Ba^{2+}$.

Which of the following elements belongs to the $second$ group and $fifth$ period of the periodic table?

Which of the following elements has two electrons in the $Q$ shell in its ground state?

$s-$block element which cannot be qualitatively confirmed by the flame test is ..... .