Chloroform reacts with concentrated $HNO_{3}$ to give

The correct description of the product in the following reaction is:
$CH_3-CH(Br)-CH_2OCH_3 \text{ } ((R)) \xrightarrow{NaCN, \text{acetone}} CH_3-CH(CN)-CH_2OCH_3$

How do polar solvents help in the first step in $S_{N}1$ mechanism?

Which reaction results in the formation of a pair of enantiomers?

Identify the Finkelstein reaction from the following.

Explain the mechanism of the bimolecular nucleophilic substitution $(S_N2)$ reaction with the example of $CH_3Cl$.