If you examined the human body on a chemical composition basis, which of the following combinations of elements would be most common?
a) o, c, n, na
b) c, h, ca, cl
c) o, c, h, n
d) c, n, ca, s
e) o, c, p, s

C) O, C, H, N

Explanation:

Roughly 96% of the mass of the human body is made up of the four elements which are carbon, oxygen, hydrogen and nitrogen.

The elements, oxygen and hydrogen are found predominantly in water, which makes up 60% of body's weight approximately. Element carbon is synonymous with life. The central role of the element, carbon is due to the fact that the carbon has 4 bonding sites which allow the element for the building of long and the complex chains of molecules. Nitrogen is found in the organic molecules, including the amino acids which make up proteins, and nucleic acids which make up DNA.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.