Question

The atomic mass of deuterium isotope of hydrogen is $2$. The atomic mass of oxygen is $16$. Then what is the molecular mass of heavy water ?

• A. $16$
• B. $18$
• C. $20$
• D. $24$

Answer 1

The correct option is C $20$

Molecular mass of heavy water $\left(D_{2}O\right)$ = ( $2\times AtomicmassofD+AtomicmassofO$ )

= $(2\times 2)+16$ = $20$

$\therefore$ Molecular mass of heavy water $\left(D_{2}O\right)$= 20.