In a nucleophilic substitution reaction,the order of halogens as incoming (attacking) nucleophiles is: $I^{-} > Br^{-} > Cl^{-}$. The order of halogens as departing (leaving) nucleophiles should be:

In nucleophilic aliphatic substitution,the nucleophiles are generally

Identify the chiral molecule from the following.

Given below are two statements:
Statement-$I$: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $S_{N}2$ mechanism.
Statement-$II$: $A$ secondary alkyl halide when treated with a large excess of ethanol follows $S_{N}1$ mechanism.
In the light of the above statements,choose the most appropriate from the options given below:

Heterolytic bond dissociation energy of alkyl halides follows the sequence:

The reaction of $n$-propyl bromide with alcoholic potassium hydroxide $(KOH)$ produces ...........