Multiple choice

Which of the following is the element least present in the human body?

  1. oxygen

  2. hydrogen

  3. iron

  4. carbon
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The human body is primarily composed of oxygen (about 65%), carbon (about 18.5%), hydrogen (about 9.5%), nitrogen (about 3.2%), calcium (about 1.5%), and phosphorus (about 1.0%). Iron, while essential for hemoglobin, constitutes only about 0.006% of body mass, making it the least abundant among these options.

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