Which of the following is most reactive toward $S_N2$ reaction?

The reaction of propylbenzene with bromine in the presence of light and heat gives ...................

In the above reaction,product $B$ is:

Examine the following statements pertaining to an $S_N2$ reaction:
$(1)$ The rate of reaction is independent of the concentration of the nucleophile.
$(2)$ The nucleophile attacks the $C$ atom on the side of the molecule opposite to the group being displaced.
$(3)$ The reaction proceeds with simultaneous bond formation and bond rupture/cleavage.
Amongst the following,which of the above are true?

What is the major product obtained in the reaction of $1-$phenyl$-2-$bromobutane with $NaOMe$?

What is the correct order of $C-X$ bond strength in $CH_{3}X$?