The number of sigma $(σ)$ and pi $(π)$ bonds in pent$-2-$en$-4-$yne is

What is the major product of the following reaction?
(Image of trans$-1,2-$dibromocyclohexane reacting with $NaNH_2$)

Arrange benzene,$n-$hexane and ethyne in decreasing order of acidic behaviour. Also give reason for this behaviour.

$A$ molecule $P$ on treatment with acid undergoes rearrangement and gives $Q$. $Q$ on ozonolysis followed by reflux under alkaline condition gives $R$. The structure of $R$ is given below:
[Image of $R$]
The structure of $P$ is

$A \xrightarrow{\Delta, 800^\circ C} CH_2=C=O$. Reactant '$A$' in the reaction is:

Methylcyclopentane $\xrightarrow{Br_2/hv} \mathop{Major}\limits_{(X)}$ $\xrightarrow[KOH/\Delta]{Alcoholic} \mathop{Major}\limits_{(Y)}$ $\xrightarrow[Peroxide]{HBr} \mathop{Major}\limits_{(Z)}$
Major final product $(Z)$ is