$SrSO_4$ has a greater solubility in water than

The pair of elements that form both oxides and nitrides when burnt in air are

Which is used to reduce the acidity of soil?

Match the following:

List-$I$	List-$II$
$I$. $CaSO_4 \cdot 2H_2O$	$A$. Knee cement
$II$. $CaSO_4 \cdot 0.5H_2O$	$B$. Gypsum
$III$. $CaSO_4$	$C$. Plaster of Paris
	$D$. Dead burnt plaster

Discuss the trend of the following:
$(i)$ Thermal stability of carbonates of Group $-2$ elements.
$(ii)$ The solubility and the nature of oxides of Group $-2$ elements.

Which one of the following is the strongest base?