Which isomer of hexane gives only two monochlorinated products?

In the given reaction,product $B$ is:
Cyclohexane $\xrightarrow{Br_2, h\nu}$ $(A) \xrightarrow{Na, \text{dry ether}}$ $(B)$

An alkane forms isomers if the number of carbon atoms is at least

The maximum number of isomers (including stereoisomers) that are possible on monochlorination of the following compound is:

$2, 3-$dimethylhexane contains tertiary,secondary,and primary carbon atoms,respectively:

Explain the formation of alkanes by Kolbe's electrolysis method with an example. Alternatively,describe the preparation of alkanes from carboxylic acids via electrolysis.