Hydroboration of $1-$methylcyclopentene using $B_2D_6,$ followed by treatment with alkaline hydrogen peroxide gives

The major products $P$ and $Q$ from the below reactions are :
$CH_3CH=CH_2 \xrightarrow{HBr} P$
$CH_3CH=CH_2 \xrightarrow[(BH_3)_2]{H_2O, H_2O_2 / OH^-} Q$

Which of the following compounds was the starting material for the oxidation shown below?
$Compound \xrightarrow{KMnO_4 / H^{\oplus}} \text{Product}$

The correct order of reactivity of hydrogen halides with propene is

Addition of $HBr$ to propene yields $2-$bromopropane,while in the presence of benzoyl peroxide,the same reaction yields $1-$bromopropane. Explain and give the mechanism.

The reaction of $1,3$-butadiene with $1$ equivalent of $HBr$ at different temperatures yields products $A$ and $B$. Identify the relationship between $A$ and $B$. The reaction scheme is as follows:
$CH_2=CH-CH=CH_2 + HBr (1 \text{ eq}) \xrightarrow{25^{\circ}C} A$
$CH_2=CH-CH=CH_2 + HBr (1 \text{ eq}) \xrightarrow{-80^{\circ}C} B$