Atomic Mass — Definition & AMU

Yes, every chlorine atom has a mass of 35.45 AMU

Yes, the most common isotope of chlorine has a mass of 35.45 AMU

No, atomic masses are always integers, the average mass of chlorine just happens to be 35.45 AMU

No, 35.45 AMU is the mass of molecular chlorine, an atom of chlorine has half of that mass.