Which of the following compounds do not undergo addition reactions?

Identify the reactivity order for halogens towards alkanes.

$LPG$ is a mixture of

Identify the major product $Y$ in the following reaction sequence:
$CH_3-CH(CH_3)-CH_2-Cl$ $\xrightarrow[\text{dry ether}]{Na} X$ $\xrightarrow[\text{monobromination}]{Br_2/h\nu} Y$ (major)

Given below are two statements $:$
Statement $(I) :$ Neopentane forms only one monosubstituted derivative.
Statement $(II) :$ Melting point of neopentane is higher than $n-$pentane.
In the light of the above statements,choose the most appropriate answer from the options given below $:$

How many pairs of enantiomers are formed during the monochlorination of $2$-methylbutane?