Which element is the most abundant by mass in the human body?

• A. Hydrogen
• B. Oxygen
• C. Carbon
• D. Nitrogen

Answer: (B)

Verified step by step guidance

1. Understand that the question asks for the element that is most abundant by mass in the human body, not by number of atoms.
2. Recall that the human body is primarily composed of water (H\_2O), and water contains oxygen and hydrogen atoms.
3. Recognize that although hydrogen atoms are more numerous, oxygen atoms have a much greater atomic mass, contributing more to the total mass.
4. Consider other major elements like carbon and nitrogen, which are important but present in smaller amounts compared to oxygen.
5. Conclude that oxygen, due to its high abundance in water and other compounds, is the most abundant element by mass in the human body.