In the reaction $2CHCl_3 + O_2 \xrightarrow{X} 2COCl_2 + 2HCl$,$X$ represents:

Which of the following cannot undergo $E_2$ reaction?

In which reaction is a racemic mixture not obtained?

$A$ solution of $(\pm)-2$-chloro-$2$-phenylethane in toluene is mixed slowly with a small amount of $SbCl_5$. The reaction proceeds due to the formation of:

Which compound in each of the following pairs will react faster in $S_N2$ reaction with $OH^{-}$?
$(i)$ $CH_3-Br$ or $CH_3-I$
$(ii)$ $CH_3-C(CH_3)_2-Cl$ or $CH_3-Cl$

The major product obtained in the following reaction is $C_2H_5ONa + (CH_3)_3C-Cl \rightarrow$