Identify the alkadiene molecule from the following.

The addition of $HI$ to the double bond of propene yields isopropyl iodide and not $n$-propyl iodide because the addition proceeds through the formation of:

The major product formed during the reaction of $1$-methylcyclopentene with $CH_3CO_3H$ is

The general formula of alkenes is:

In the following reaction,$P$ gives two products $Q$ and $R$ each in $40 \,\%$ yield. If the reaction is carried out with $420 \,mg$ of $P$,the reaction yields $108.8 \,mg$ of $Q$. The amount of $R$ produced in the reaction is closest to $....\, mg$.

$3-$Methylpent$-2-$ene on reaction with $HBr$ in the presence of peroxide forms an addition product. The number of possible stereoisomers for the product is: