The best method for preparing alkyl chloride is:

When toluene is treated with $Br_2$ in the presence of sunlight,it mainly gives:

The products $A$ and $B$ obtained in the following reactions,respectively,are
$3 ROH + PCl_3 \rightarrow 3 RCl + A$
$ROH + PCl_5 \rightarrow RCl + HCl + B$

Which one of the following reactions would be the best for the formation of $2-$bromobutane?
$(1)$ $CH_3CH=CHCH_2CH_3$ $\xrightarrow{HBr}$
$(2)$ $CH_3CH_2CH=CH_2$ $\xrightarrow{HBr}$
$(3)$ $CH_3CH=CHCH_3$ $\xrightarrow{Br_2}$
$(4)$ $CH_3CH_2CH=CH_2$ $\xrightarrow[Peroxide]{HBr}$

In the preparation of $CHCl_3$ from ethanol and bleaching powder,the latter provides:

Identify the correct products when ethanol reacts with $PCl_5$.