D2O is:
Used in nuclear reactors as a moderator to slow down fast-moving neutrons
Used as a tracer compound
Chemically identical to water but has higher molar mass
For a similar reaction under similar conditions, s reaction speed/rate tends to be lesser than that of
The chemical properties of heavy water are almost similar to that of normal H2O. In most cases, the reaction speed/rate is usually lesser. D2O is used to understand the reaction mechanisms in organic chemistry where different bond cleavages are possible (It is used as a tracer compound). In nuclear reactors, heavy water is used as a moderator to slow down fast-moving neutrons