The human body contains an average of 65% oxygen, 18% carbon, 10% hydrogen, 0.15% sodium and 0.15% chlorine.

The human body contains an average of 65% oxygen, 18% carbon, 10% hydrogen, 0.15% sodium and 0.15% chlorine. Arrange the above-named chemical elements in order of decreasing number of their atoms contained in the human body.

1) Calculation of the amount of substance of atoms of each element according to the formula n (E) = m (E) / Ar (E)
n (O) = m (O) / Ar (O) = 65: 16 = 4.06 mol of oxygen atoms
n (C) = m (C) / Ar (C) = 18: 12 = 1.5 mol of carbon atoms
n (H) = m (H) / Ar (H) = 10: 1 = 10 mol of hydrogen atoms
n (Na) = m (Na) / Ar (Na) = 0.15: 23 = 0.065 mol of sodium atoms
n (Cl) = m (Cl) / Ar (Cl) = 0.15: 35.5 = 0.0042 mol of chlorine atoms
2) The number of atoms of an element is directly proportional to the amount of substance of the element.
Comparing the amount of substance of the atoms of each element, we find that in decreasing order, the atoms are arranged in the following sequence: hydrogen, oxygen, carbon, sodium, chlorine