Which of the following will give two isomeric monochloro derivatives?

In the following sequence of reactions,the $P$ is:

$C_3H_8 + Cl_2 \xrightarrow{\text{Light}} C_3H_7Cl + HCl$ is an example of which of the following types of reactions?

Consider the following reaction:
$H_3C-CH(D)-CH(CH_3)-CH_3 + Br^\bullet \to X + HBr$
Identify the structure of the major product $X$.

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)

$CH_3-CH_2-CH_2-CH_3 \xrightarrow{Br_2/hv}$
Major product in the above reaction is