Question

The atomic mass of chlorine represents the mass of the most common naturally occurring isotope of chlorine. Is the statement true or false and why?

Answer 1

false, because the atomic mass represents the averages by percent abundance of all the isotopes of Chlorine.
Chlorine's atomic mass is 35.453 g/mol
That means that 35 is most prevalent, but there is some 36 (and maybe even 34 or 37) in there too.