[LOLLOLLOL]

Why is carbon-12 the only isotope with an atomic mass that is a whole number?
 I only know that carbon-12 is the standard, u = 1/12 of the mass of one atom of carbon-12, but why is it the only one with a whole number atomic mass?

Why does the abundance and the mass of the radioisotopes of silver not used to calculate the average atomic mass of silver?
Is it that radioisotopes are unstable and not related to silver??

[ARGOS++]

Dear LOLLOLLOL;

That’s no surprise!, because C⁽¹²⁾ is by definition the base of the “whole” Mass-System.

Usually for mass calculation only the stabile or only the ones with longest life-time are considered/included.

Good Luck!
                   ARGOS⁺⁺