The colour given to the flame by sodium salts is

$A$ compound $(M_2O_2)$ of group $I$ element $(M)$ hydrolyses to form $M^{+}$,$OH^{-}$ and $X$. Another compound $(M'O_2)$ of group $I$ element $(M')$ hydrolyses to form $(M')^{+}$,$OH^{-}$,$X$ and $Y$. What are $X$ and $Y$ respectively?

Which of the following elements has the highest reaction rate with water?

$A$ metal $X$ on heating in nitrogen gas gives $Y$. $Y$ on reaction with ${H_2}O$ produces a colourless gas. When this gas is passed through $CuSO_4$ solution,it gives a blue colour. What is $Y$?

What is produced when sodium nitrate is heated at $800 \, ^oC$?

Correct order of solubility is