Which of the following substances is used in gunpowder?

Which elements of group-$1$ and group-$2$ differ from the other elements of the same group?

$A$ metal $M$ reacts with nitrogen gas to afford $M_3N$. $M_3N$ on heating at high temperature gives back $M$ and on reaction with water produces a gas $B$. Gas $B$ reacts with aqueous solution of $CuSO_4$ to form a deep blue compound. $M$ and $B$ respectively are

The correct order of hydration enthalpies of alkali metal ions is

Which compounds are found as impurities in impure sodium chloride?

Which of the following statement$(s)$ is (are) correct?
$(i)$ $LiF$ is less soluble in water
$(ii)$ $NaCl$ is less ionic than $CsCl$
$(iii)$ Formation of alkali metal halide is an endothermic reaction