Which metal has $2$ electrons in the outermost orbit?

Bleaching powder is obtained by passing chlorine on

Identify the option in which the trends corresponding to hydroxides of group $2$ elements (from $Mg(OH)_2$ to $Ba(OH)_2$) are correctly shown:

Basic character

Chemical stability

Solubility

Addition of an oxalate solution to an aqueous solution containing a mixture of $Ba^{2+}$,$Sr^{2+}$,and $Ca^{2+}$ ions will precipitate:

Which of the following statements is false?

Plaster of Paris is used: