Question

The most abundant elements by mass in the body of a healthy human adult are: Oxygen $\left(61.4\%\right)$, Carbon $\left(22.9\%\right)$, Hydrogen $\left(10.0\%\right)$ and Nitrogen $\left(2.6\%\right)$. The weight which a 75 kg person would gain if all $H^1$ atoms are replaced by $H^2$ atoms is:

• A. 15 $kg$
• B. 7.5 $kg$
• C. 10 $kg$
• D. 37.5 $kg$

Answer 1

The correct option is B 7.5 $kg$

Total hydrogen ${(}_1{H}^1)=\frac{10}{100}\times 75=7.5kg$

If it is replaced by ${}_1{H}^2$ then mass will be doubled so now hydrogen mass = 15 $kg$

So, mass of person will be increased by 7.5 $kg$.