Question

A metal $M$ readily forms water soluble sulphate $MS{O}_4$, water insoluble hydroxide $M(OH{)}_2$ and oxide $MO$ which becomes inert on heating. The hydroxide is soluble in $NaOH$. The $M$ is

• A. $Be$
• B. $Mg$
• C. $Ca$
• D. $Sr$

Answer 1

The correct option is A $Be$

In group 2, the solubility of sulphates decrease down the group. Be and Mg sulphates are highly soluble due to high enthalpy of solvation of smaller $B{e}^{2+}\text{and}M{g}^{2+}$ ions.
BeO and MgO are non reactive on heating, hence they are used in lining furnaces.
$Be(OH{)}_2$ is amphoteric in nature but the hydroxides of Mg, Ca and Sr are basic. Hence $Be(OH{)}_2$ will dissolve both in acids and alkali.
$Be(OH{)}_2+H_{2}S{O}_4\to N{a}_{2}Be(OH{)}_4$