What effect does branching of an alkane chain have on its boiling point?

$C_8H_{18}$ $(A)$ on mono-chlorination forms only one type of $C_8H_{17}Cl$ $(B)$. Hence $(A)$ can be:

Consider the following:
Statement-$I$ : Kolbe's electrolysis of sodium propionate gives $n$-hexane as product.
Statement-$II$ : In Kolbe's process,$CO_2$ is liberated at the anode and $H_2$ is liberated at the cathode.
The correct answer is:

$(i)$ Give the reaction for the bromination of ethane.
$(ii)$ Is this reaction suitable for obtaining pure bromoethane? Why?
$(iii)$ Give the name of the reaction mechanism and the names of the stages occurring in the reaction.
$(iv)$ Give the reaction for the first stage.
$(v)$ Which type of bond cleavage occurs in the first stage?

When the fuel mainly contains ...............,knocking occurs more in the engine.

On halogenation,an alkane gives only one monohalogenated product. The alkane may be