Which among the following reactions is used for the preparation of alkyl fluorides?

$2-$methylpropane can be prepared by the Wurtz reaction. The haloalkanes taken along with metallic sodium and dry ether are:

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

The best method for preparing alkyl chloride is:

Identify the name of the reaction in which alkyl fluorides are prepared by heating alkyl bromide or alkyl chloride with metallic fluorides like $AgF$,$Hg_2F_2$,$CoF_2$,or $SbF_3$.

Grignard reagent is not prepared in an aqueous medium but is prepared in an ether medium because: