When vegetation is burnt in the absence of oxygen,which of the following will be formed?

Which of the following statements is true?

$A$ gaseous alkane undergoes complete combustion with oxygen. The ratio of the volume of $O_2$ required to the volume of $CO_2$ formed is $7 : 4$. The molecular formula of the alkane is:

Halogenation of alkanes is:

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)

One mole of an alkane $(x)$ requires $8$ mole oxygen for complete combustion. The sum of the number of carbon and hydrogen atoms in the alkane $(x)$ is . . . . . . .