Question

The percentage weight of deuterium in heavy water is:

• A. $80$%
• B. $60$%
• C. $40$%
• D. $20$%

Answer 1

Answer: (D)

$20$%

Heavy water $\left(D_{2}O\right)$ is also called $deuteriumoxide$.

Deuterium, the hydrogen isotope has a mass double of that of ordinary hydrogen.

The molecular weight of $D_{2}O=2\left(2\right)+16=20g/mol$

The percentage weight of deuterium in heavy water is$=\frac{4}{20}\times 100=20$%