Question

A scientist is examining the role of an element found in fats and carbohydrates of living things. This element makes up 65% of human body mass. Which statement describes the element he is studying?

Answer 1

This element is found in fats and carbohydrates and makes 65%of human body mass

Answer 2

General structure of carbohydrate is (CH₂O)n.

General structure of fatty acids(structural units of fats and oils) is a long chain hydrocarbon chain(which consists C and H) with a terminal carboxylic group  (-COOH).

Now if we consider number of the atoms H or hydrogen has the largest among all but it has a atomic mass of 1.008 amu while C or carbon has 12 amu and O or oxygen has 16 amu.

Now in carbohydrates the mass of O exceeds C but in fats mass of C is much more greater than O [ for example, in Oleic acid, C₁₈H₃₄O₂; difference in masses can be clearly seen and now imagine our body fats are consist of huge number of fatty acid units.]

Thus, Carbon is the element which makes up 65% of human body mass.