Mostly elements have fractional atomic masses because of

Explanation

Most elements exist as a mixture of isotopes, each with a slightly different mass due to variations in the number of neutrons. Atomic masses reported on the periodic table are weighted averages of the masses of these isotopes, taking into account their relative abundance in nature.Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. Since different isotopes have different masses, the atomic mass reported for an element reflects the weighted average of these isotopic masses, considering their abundance in nature.For example, carbon has two stable isotopes, carbon-12 and carbon-13, with natural abundances of approximately 98.9% and 1.1%, respectively. The atomic mass of carbon on the periodic table is approximately 12.01 u, reflecting the average mass of carbon atoms in naturally occurring samples, accounting for the contributions of both isotopesTherefore, option (c) accurately describes why elements have fractional atomic masses.