Explanation

(c)
When an alkyl halide reacts with sodium in presence of dry ether, an alkane with the double number of carbon atoms than the parent halide, is obtained and this reaction is known as Wurtz reaction.
4 3 2
$CH_{3} - CH - CH - Cl$
| |
$CH_{3}\ \ \ \ {CH}_{3}$
2-chloro-3-methyl butane
3 2
$+ CH_{3} - CH - CH - Cl\underset{\begin{array}{r}
Dry\ ether \\
- 2NaCl
\end{array}}{\overset{\ \ \ \ Na\ \ \ \ \ \ \ \ \ \ \ \ }{\rightarrow}}$
| |
$CH_{3}\ \ \ \ \ {CH}_{3}$
6 5 4 3 2 1
$CH_{3} - CH - CH - CH - CH - {CH}_{3}$
| | | |
$CH_{3}\ \ \ \ {CH}_{3}\ \ \ \ \ {CH}_{3}\ \ \ {CH}_{3}$
2,3,4,5-tetramethyl hexane