Identify the halogen exchange reaction from the following.

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

Identify the reactions that are correctly matched with their major product.

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

Which reagent cannot be used to prepare an alkyl halide from an alcohol?

Finkelstein reaction is used for the synthesis of