In the reaction $\left(\mathrm{X}\right)$ and $\left(\mathrm{Y}\right)$ are respectively.

The given reaction is for preparation of $\mathrm{DDT}$ (dichlorodiphenyl trichloroethane). Complete reaction is given as follows.

(i)

(ii) 

Dichloro-diphenyl-trichloroethane (DDT) is prepared by heating chloral and chlorobenzene in 1:2 ratio in the presence of conc. sulphuric acid.

DDT is used as an insecticide. It is also used as a mosquito repellant.