Which of the following will release hydrogen gas upon reaction with hydrochloric acid?

Chile saltpetre is

Which among the following elements develops noble gas configuration in $+1$ state?

The alkali metal with the lowest $E^{\circ}_{M^{+}/M} (V)$ is $X$ and the alkali metal with the highest $E^{\circ}_{M^{+}/M} (V)$ is $Y$. Then $X$ and $Y$ are respectively:

Crude sodium chloride obtained by crystallisation of brine solution does not contain

In the synthesis of sodium carbonate,the recovery of ammonia is done by treating $NH_4Cl$ with $Ca(OH)_2$. The by-product obtained in this process is