Reaction of $HBr$ with propene in the presence of peroxide gives

For which of the following reactions is Markovnikov's rule most applicable?

What do you mean by alkene? Give its general formula and two examples.

The major product of the following reaction is:

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.

Identify the major product $X$ in the following reaction:
$1,5,5-\text{trimethylcyclohex-1-ene} \xrightarrow{N.B.S., h\nu} X$