The most abundant elements by mass in the body of a healthy human adult are: oxygen ( $61.4 \%$ ), c

Question

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 ${ }^{1} \mathrm{H}$ atoms are replaced by ${ }^{2} \mathrm{H}$ atoms is\

Professor PC Thomas Classes · Answer

(a) : Mass of elements in the body of a healthy human adult are :\ Oxygen ( $61.4 \%$ ), carbon ( $22.9 \%$ ), hydrogen ( $10.0 \%$ ) and nitrogen ( $2.6 \%$ ).\ Weight of the person $=75 \mathrm{~kg}$\ Mass due to ${ }^{1} \mathrm{H}=75 	imes \frac{10}{100}=7.5 \mathrm{~kg}$\ On replacing ${ }^{1} \mathrm{H}$ by ${ }^{2} \mathrm{H}, 7.5 \mathrm{~kg}$ mass would replace with 15 kg .\ $	herefore \quad$ Net mass gained by person $=(15-7.5) \mathrm{kg}=7.5 \mathrm{~kg}$\