Multiple choice

The four most common elements in living organisms in order are

  1. Carbon, hydrogen, oxygen, nitrogen

  2. Hydrogen, oxygen, carbon, nitrogen

  3. Hydrogen, carbon, oxygen, nitrogen

  4. Carbon, oxygen, hydrogen, nitrogen
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In living organisms, the four most common elements by number of atoms are: Hydrogen (most abundant), followed by Oxygen, Carbon, and Nitrogen. This order (H > O > C > N) reflects their abundance in biological molecules like water, proteins, carbohydrates, and nucleic acids. Option C correctly lists them in this order by atomic count.

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