Which of the following is not a biopolymer?

What is produced when ethanol reacts with sodium metal?

An organic compound $A$ of molecular formula $C_{2}H_{4}$ on reduction gives another compound $B$ of molecular formula $C_{2}H_{6}$. $B$ on reaction with chlorine in the presence of sunlight gives $C$ of molecular formula $C_{2}H_{5}Cl$.
$(a)$ Name the compounds $A, B$ and $C$.
$(b)$ Write the chemical equation for the conversion of $A$ to $B$ and name the type of reaction.

Write the name of the next homologue of $CH_{3}OH$ and $HCOOH$.

Which type of compound is formed,if one hydrogen of an alkane compound is substituted by a hydroxyl $[-OH]$ group?

Why are detergents preferred over soaps for washing clothes in hard water? Explain.