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

Question

$\begin{array}{1 1} (1) 7.5\; kg \\ (2) 10\; kg \\ (3) 15\; kg \\ (4) 37.5 kg \end{array}$