Quote:
2. the most abundant element in the human body is :
a. Carbon b. Hydrogen c. Oxygen d. Nitrogen
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By mass, human cells consist of 65-90% water (H2O), and a significant portion is composed of carbon-containing organic molecules. Oxygen therefore contributes a majority of a human body's mass, followed by carbon. 99% of the mass of the human body is made up of the six elements oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.
element abundance
Oxygen 65%
Carbon 18%
Hydrogen 10%
Nitrogen 3%
Calcium 1.5%
Phosphorus 1.0%
Potassium 0.35%
Sulfur 0.25%
Sodium 0.15%
Magnesium 0.05%
Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron 0.70%
Lithium, Strontium, Aluminum, Silicon, Lead, Vanadium, Arsenic, Bromine trace amounts
So janab the answer is neither Carbon nor hydrogen but Oxygen.
Found at:
http://chemistry.about.com/cs/howthi...dyelements.htm
Reference: H. A. Harper, V. W. Rodwell, P. A. Mayes, Review of Physiological Chemistry, 16th ed., Lange Medical Publications, Los Altos, California 1977.