Which of the following structures represents $1,3\text{-butadiene}$?

One mole of alkene $\underline{X}$ on ozonolysis gave one mole of acetaldehyde and one mole of acetone. The $IUPAC$ name of $\underline{X}$ is

Choose the correct option for the following reactions.

The product $(P)$ is:

The reaction of isobutene with $HBr$ yields:

In the following sequence of reactions,the alkene affords the compound $B$.
$CH_3-CH=CH-CH_3$ $\xrightarrow{O_3} A$ $\xrightarrow[Zn]{H_2O} B$
The compound $B$ is: