Identify reagent B in following reaction.
$\text{R}-\text{X} \xrightarrow{\ \large{\text{B}}\ } \text{Nitroalkane}$

Which of the following $n$ mole compound is obtained when $2n$ moles of $\text{C}_6\text{H}_5\text{Cl}$ treated of with $2n$ mole sodium atom in dry ether?

Which from the following compounds is not obtained when methyl bromide is treated with ethyl bromide in presence of sodium metal in dry ether?

Which of the following pair of reagents is used for the conversion of carboxylic acid to alcohol ?