What happens when methane reacts with concentrated $HNO_3$ at high temperature?

Identify the major product $'E'$ in the following reaction sequence:
Cyclohexane $\xrightarrow{Br_2, h\nu} (A)$ $\xrightarrow{Na, D.E.} (B)$ $\xrightarrow{Br_2, h\nu} (C)$ $\xrightarrow{H_2O} (D)$ $\xrightarrow{conc. H_2SO_4} (E)$

Identify the product $C$ in the following reaction:
$CH_{3}CH_{2}COOH$ $\xrightarrow{NaOH} A$ $\xrightarrow{NaOH, CaO, \Delta} B$ $\xrightarrow{HNO_{3}, \Delta} C$

$A$ mixture of ethyl iodide and $n-$propyl iodide is subjected to Wurtz reaction. The hydrocarbon that will not be formed is

Of the five isomeric hexanes,the isomer which can give two monochlorinated compounds is

What are $X$ and $Y$ respectively in the following reaction sequence?
Isopentane $\xrightarrow{KMnO_4} X$ $\xrightarrow{\text{dehydration}} \underset{\text{Major}}{Y}$