Which among the following is most reactive via $S_N2$ mechanism?

What is the major product of the following reaction?
$CH_2=CH-CH_2-CH(Br)-CH_3 + KOH \xrightarrow[\text{heat}]{\text{alcohol}} \dots$

Which of the following alkyl halides is most reactive towards the $E_2$ mechanism?

Given below are two statements $:$
Statement $(I) :$ Alcohols are formed when alkyl chlorides are treated with aqueous potassium hydroxide by elimination reaction.
Statement $(II) :$ In alcoholic potassium hydroxide,alkyl chlorides form alkenes by abstracting the hydrogen from the $\beta-$carbon.
In the light of the above statements,choose the most appropriate answer from the options given below $:$

Which of the following isomers of $C_4H_9Br$ is a chiral molecule?

The reaction $(CH_3)_3C - Br + H_2O \rightarrow (CH_3)_3C - OH + HBr$ is an example of which type of reaction?