Which of the following hydrides are ionic?

The correct order of melting point for alkaline earth metals is:

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 $R$.

What is the substance known as 'blanc fixe' used in paints?

$X$-ray tube windows are made using which of the following metals?

Compounds of alkaline earth metals are less soluble in water than the corresponding alkali metal compounds due to