When chloroform is treated with conc. $HNO_3$,it gives:

Tertiary alkyl halide is practically $inert$ to substitution by $S_{N}2$ mechanism because of:

The optically inactive compound from the following is

Which alkyl halide from the following pairs would you expect to react more rapidly by an $S_N2$ mechanism? Explain your answer.
$(i)$ $CH_3CH_2CH_2CH_2Br$ or $CH_3CH_2CH(Br)CH_3$
$(ii)$ $CH_3CH_2CH(Br)CH_3$ or $(CH_3)_3CBr$
$(iii)$ $CH_3CH(CH_3)CH_2CH_2Br$ or $CH_3CH_2CH(CH_3)CH_2Br$

Which of the following reactants will not favour nucleophilic substitution reaction?

Correct order of nucleophilicity for $S_N2$ reaction