Preparation of alkyl halides in the laboratory is least preferred by:

Which of the following reaction$(s)$ can be used for the preparation of alkyl halides?
$I$. $CH_3CH_2OH + HCl \xrightarrow{Anh. ZnCl_2}$
$II$. $CH_3CH_2OH + HCl \rightarrow$
$III$. $(CH_3)_3COH + HCl \rightarrow$
$IV$. $(CH_3)_2CHOH + HCl \xrightarrow{Anh. ZnCl_2}$

Identify the Swarts reaction from the following:

Assertion : Alkyl iodide can be prepared by treating alkyl chloride/bromide with $NaI$ in acetone.
Reason : $NaCl/NaBr$ are soluble in acetone while $NaI$ is not.

Identify the halogen exchange reaction from the following.

The starting substance for the preparation of $CH_3I$ is