What is the molecular formula of sodium ethanoate?

Ethanol reacts with sodium and forms two products. These are

In the modern industrial method for the production of ethanol, hydration of ethene is carried out in the presence of which substance?

What is the common name of ethanoic acid?

$A$ compound $C$ (molecular formula $C_2H_4O_2$) reacts with $Na$ metal to form a compound $R$ and evolves a gas which burns with a pop sound. Compound $C$ on treatment with an alcohol $A$ in the presence of an acid forms a sweet-smelling compound $S$ (molecular formula $C_3H_6O_2$). On addition of $NaOH$ to $C$,it also gives $R$ and water. $S$ on treatment with $NaOH$ solution gives back $R$ and $A$. Identify $C$,$R$,$A$,$S$ and write down the reactions involved.

What is the molecular formula of formalin?