What is heavy water? Give its uses.

(N/A) Heavy water,denoted as $D_{2}O$,is an oxide of deuterium,which is an isotope of hydrogen.
Heavy water is injurious to human beings,plants,and animals because it slows down the rates of biochemical reactions occurring in them. Consequently,it does not support life and is not suitable for drinking.
Uses of heavy water:
$1$. It is extensively used as a moderator in nuclear reactors to slow down fast-moving neutrons.
$2$. It is used in exchange reactions to study reaction mechanisms.
$3$. It serves as a tracer compound in various chemical and biological studies.
Chemical reactions involving heavy water:
$CaC_{2} + 2D_{2}O \longrightarrow C_{2}D_{2} + Ca(OD)_{2}$
$SO_{3} + D_{2}O \longrightarrow D_{2}SO_{4}$
$Al_{4}C_{3} + 12D_{2}O \longrightarrow 3CD_{4} + 4Al(OD)_{3}$