Alkaline earth metals are denser than alkali metals,because metallic bonding in alkaline earth metals is:

Among the following,which is water insoluble?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Barium carbonate is insoluble in water and is highly stable.
Reason $R$: The thermal stability of the carbonates increases with increasing cationic size.
Choose the most appropriate answer from the options given below for $A$ and $R$.

Assertion : Barium is not required for normal biological function in humans.
Reason : Barium does not show variable oxidation states.

Which of the following carbonates undergoes decomposition upon heating?

Write down the preparation,properties,and uses of Calcium sulphate $(CaSO_{4} \cdot \frac{1}{2} H_{2} O)$ (Plaster of Paris).