What is the product obtained when phenylethene is treated with $KMnO_4$ in dilute $H_2SO_4$?

Which of the following reactions generates the major product shown?

Assertion $(A)$: Propene on addition with hydrogen bromide in the presence of peroxide gives $1-$bromopropane as the major product.
Reason $(R)$: $1-$bromopropane is the major product because it is formed through the stable carbocation.
The correct answer is

Assertion : $1$-Butene on reaction with $HBr$ in the presence of a peroxide produces $1$-bromobutane.
Reason : It involves the free radical mechanism.

Explain the dehalogenation of vicinal dihalides with an example.

The reaction $CH_2 = CH - CH_3 + HBr \rightarrow CH_3CHBr - CH_3$ is