Q. Which elements are most abundant in living organisms?
a. oxygen, nitrogen, carbon, hydrogen, sulfur, and phosphorus
b. carbon, potassium, iron, magnesium, hydrogen, and nitrogen
c. hydrogen, carbon, calcium, potassium, oxygen, and phosphorus
d. oxygen, calcium, phosphorus, sodium, hydrogen, and carbon
Living organisms often contain trace amounts of several elements, but the most abundant ones are oxygen, carbon, hydrogen, nitrogen, calcium, sulfur and phosphorus.