$KCN$ reacts readily to give a cyanide with:

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

Which of the following compounds is not a suitable solvent for a Grignard reaction?

The major product in the reaction is:

An 'Assertion' $(A)$ and a 'Reason' $(R)$ are given below. Choose the correct answer from the following options.
Assertion $(A)$: Vinyl halides do not undergo nucleophilic substitution easily.
Reason $(R)$: Even though the intermediate carbocation is stabilized by loosely held $p-$ electrons,the cleavage is difficult because of strong bonding.

Which of the following alkyl halides is most reactive towards substitution by the $S_{N}1$ mechanism?