The reaction in which 2 molecules of chlorobenzene reacts with metallic sodium in presence of dry ether forming diphenyl is an example of,

Propene when treated with cold conc. $\mathrm{H}_2 \mathrm{SO}_4$ forms a compound which on heating with water gives

How many gram of sodium (atomic mass $23u$) is required to prepare one mole of ethane from methyl chloride by Wurtz reaction?

In the reaction,

$2 n R-X \xrightarrow[\text { Dry ether }]{+2 n \mathrm{Na}}$ product

The product obtained is