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

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

Answer 1

Correct option: (D)

The most abundant elements by mass in the body of a healthy human adult has:-

Oxygen $=61.4$%

Carbon $=22.9$%

Hydrogen $=10.0$%

Nitrogen $=2.6$%

Step 1: Calculating the mass of ${}^{1}H$ in $75kg$ person

Mass of hydrogen $=10$%

Mass of hydrogen in $75kg$ person $=\frac{75}{100}\times 10=7.5kg$

Step 2: Calculating the change

Mass of ${}^{2}H=2{(}^{1}H)$

So, mass of ${}^{2}H$ in $75kg$ person $=2\times 7.5=15kg$

Hence, change in mass $=15-7.5=7.5kg$

Hence, the correct option is (D).