What is the product formed when $Zn$ reacts with an excess of $NaOH$?

$P \xrightarrow{\Delta } Q$ (metallic solid) $+ R \uparrow + S \uparrow$
$X \xrightarrow{\Delta } Y$ (amphoteric oxide) $+ R \uparrow + S \uparrow$
$P$ and $X$ are respectively:

The solution of sodium metal in liquid ammonia is strongly reducing due to the presence of which of the following in the solution?

Compound $A$ reacts with $NH_4Cl$ and forms a compound $B$. Compound $B$ reacts with $H_2O$ and excess of $CO_2$ to form compound $C$,which on reaction with saturated $NaCl$ solution forms sodium hydrogen carbonate. Compounds $A, B$ and $C$ are respectively:

The reactivity of $Na$ metal with water is utilized in which of the following processes?

Which of the following metal ion plays an important role in muscle contraction?