Which of the following tests is used for the detection of glucose?

$A$ gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.

What is the monomer unit of neoprene?

Draw the structural formula of methanoic acid.

$(i)$ What is vinegar? State its one use.
$(ii)$ Which gas is produced when dilute ethanoic acid is added to sodium bicarbonate? How will you test the presence of this gas?

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.