The product obtained by heating $(NH_4)_2SO_4$ and $KCNO$ is

Give the reactions for the following conversions:
$1$. Polyvinyl chloride from ethyne
$2$. Methane from propyne
$3$. $2,3-$Dimethylbutane from propene

Which of the following reactions do not represent the major product of given Birch reductions?

In the reaction,
$C_5H_6 + CH_3COCH_3 \xrightarrow{EtONa/EtOH, \text{heat}} X$,
the product $(X)$ is

Arrange the compounds $I$,$II$,and $III$ in decreasing order of their heats of combustion.

What is the degree of unsaturation (double bond equivalent) in compound $(A)$?