What is the general formula for the corresponding alcohol of an alkane?

Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of

$A$ 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.

List two characteristic features of carbon which,when put together,give rise to a large number of carbon compounds.

The structural formula of ethyne is:

What is the name of the aldehyde corresponding to methane?