Which of the following is a component of baking powder?

$A$ metal $M$ reacts with $N_2$ to form a compound $A$ $(M_3N)$. Heating $A$ at a high temperature gives back $M$,and passing $A$ through $H_2O$ results in the evolution of gas $B$. Gas $B$ turns $CuSO_4$ solution blue. What are $A$ and $B$ respectively?

The alkali metals form salt-like hydrides by direct synthesis at elevated temperatures. The thermal stability of these hydrides decreases in which of the following orders?

Which of the following statements is correct?

On heating,$LiNO_3$ gives how many compounds among the following?
$Li_2O, N_2, O_2, LiNO_2, NO_2$

What is the correct order of ionic mobility for alkali metal ions in an aqueous medium?