Nitrates of all the metals are

What is the chemical formula of Indian saltpeter?

Which of the following compounds release oxygen upon heating?

The frequency of the radiation emitted by alkali metals in the flame test follows the order:

Given below are two statements,one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The alkali metals and their salts impart characteristic colour to reducing flame.
Reason $R$: Alkali metals can be detected using flame tests.
In the light of the above statements,choose the most appropriate answer from the options given below.

In certain properties,lithium differs from other alkali metals. The main reason for this is: