In the preparation of Grignard reagent from haloalkane,the metal used is:

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.

Ethanol is converted into ethyl chloride by reacting with

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

The preparation of alkyl halides in the laboratory is least preferred by:

$2$-Bromobutane is obtained by the reaction of: