Which of the following compounds transforms baking soda into baking powder?

Identify the product when magnesium burns in air.

Which among the following alkali metal chlorides crystallises in the form of a hydrate?

Which of the following metals liberate hydrogen gas on reaction with dilute $H_2SO_4$?

Which of the following does not liberate a brown gas?

$A$ 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