Plaster of Paris is hardened by

Which of the following on thermal decomposition gives both basic and acidic oxides?

Identify the correct statements from the following:
$I$. All alkaline earth metals give hydrides on heating with hydrogen.
$II$. Calcium hydroxide is used to purify sugar.
$III$. $BeCl_2$ is a dimer in gaseous phase.

All the elements of group $2$ react with water to form metal hydroxide and hydrogen,except the element

$Be$ and $Al$ exhibit many properties which are similar,but the two elements differ in:

Which of the following substances is the least soluble in water?