What are $\mathrm{X}$ and $\mathrm{Y}$ respectively in the following reactions

$\underset{¯}{\mathrm{X}}+{\mathrm{D}}_2\mathrm{O}\to {\mathrm{C}}_2{\mathrm{D}}_2+\mathrm{P}$

$\underset{¯}{\mathrm{Y}}+{\mathrm{D}}_2\mathrm{O}\to {\mathrm{CD}}_4+\mathrm{Q}$

Statements about heavy water are given below.

A. Heavy water is used in exchange reactions for the study of reaction mechanisms.

B. Heavy water is prepared by exhaustive electrolysis of water.

C. Heavy water has higher boiling point than ordinary water.

D. Viscosity of ${\mathrm{H}}_2\mathrm{O}$ is greater than ${\mathrm{D}}_2\mathrm{O}$.

Choose the most appropriate answer from the options given below:

The correct match is

Which of the following statements about heavy water are correct?

$\left(\mathrm{a}\right)$ Heavy water is used as a moderator in nuclear reactors.

$\left(\mathrm{b}\right)$ Heavy water is more associated than ordinary water.

$\left(\mathrm{c}\right)$ Heavy water is a more effective solvent than ordinary water.

Which of the following statement(s) is(are) correct?

$\left(\mathrm{A}\right)$ Heavy water is used as a moderator in a nuclear reaction.

$\left(\mathrm{B}\right)$ Heavy water is more associated than ordinary water.

$\left(\mathrm{C}\right)$ Heavy water is a more effective solvent than ordinary water.