Which one of the following dienes would you expect to be the most stable?

Compound $(C)$ in the above sequence of reaction is:

An unsaturated hydrocarbon $X$ absorbs two hydrogen molecules on catalytic hydrogenation,and also gives the following reaction: $X$ $\xrightarrow[Zn/H_2O]{O_3} A$ $\xrightarrow{[Ag(NH_3)_2]^{+}} B$ ($3$-oxo-hexane dicarboxylic acid). $X$ will be

In the following reactions,the product $S$ is

What is the number of moles of $sp^2$ hybrid carbon atoms in one mole of $hexa-1,4-diyne$?

Answer the following questions:
$(i)$ Give hybridization of Carbon atoms in the following compound: $CH_3-CH=CH-CH_2-C\equiv CH$
$(ii)$ Give the number of $\sigma$ and $\pi$ bonds in the above compound.
$(iii)$ Give the $IUPAC$ name of the above compound.
$(iv)$ Draw the geometrical isomers of the above compound.
$(v)$ Why are $cis$ and $trans$ isomers not possible in alkynes?
$(vi)$ Which bond possesses more bond length between $C=C$ and $C\equiv C$?