The reagent used to convert an alkyne to an alkene is:

One mole of $1, 2-$dibromopropane is reacted with $x$ moles of $NaNH_2$ followed by treatment with ethyl bromide to yield a pentyne. What is the value of $x$?

Identify the alkyne in the following sequence of reactions:
Alkyne $\xrightarrow{\text{H}_2, \text{Lindlar's catalyst}} A$ $\xrightarrow{\text{Ozonolysis}} B \text{ (only)}$
Given that $B$ is obtained from $\text{CH}_2=\text{CH}_2$ via the Wacker process.

Which of the following reactions will yield $2, 2-$dibromopropane?

$CH_3-C \equiv CH \xrightarrow[dil. H_2SO_4]{HgSO_4} (A)$
$CH_3-C \equiv CH \xrightarrow[(1) BH_3.THF]{(2) H_2O_2/HO^{-}} (B)$
Products $(A)$ and $(B)$ can be differentiated by:

In which of the following molecules,$2$ $\pi$ bonds are present?