Deuterium oxide (D2O) is water in which the protons (1H) have been replaced by their heavier isotope

Question:

Deuterium oxide (D2O) is water in which the protons (1H) have been replaced by their heavier isotope deuterium (2H). It is readily available and is used in a variety of mechanistic studies in organic chemistry and biochemistry. When D2O is added to an alcohol (ROH), deuterium replaces the proton of the hydroxyl group.