In the combustion of hydrocarbons,$\Delta H$ is

Which one of the following is the intermediate in the preparation of a ketone by hydration of an alkyne in the presence of sulfuric acid and mercury $(II)$ sulphate?

Compound $X$ of molecular formula $C_4H_6$ takes up one equivalent of hydrogen in the presence of $Pt$ to form another compound $Y$,which on ozonolysis gives only ethanoic acid. The compound $X$ can be:

$A$ mixture of $C_2H_6, C_2H_4$ and $C_2H_2$ is bubbled through an alkaline solution of copper$(I)$ chloride,contained in a Woulf's bottle. The gas coming out is

In the given sequence of reactions,identify $P, Q, R$ and $S$ respectively.
$CH_2=CH_2 + Br_2$ $\xrightarrow{P} CH_2(Br)-CH_2(Br)$ $\xrightarrow{Q} CH_2=CH-Br$ $\xrightarrow{R} CH \equiv CH$ $\xrightarrow{S} C_6H_6$

Name the distinguishing reaction of an alkane from an alkene.