The average atomic mass of chlorine is 35.5 u. Do we come across a sample of the element with atomic mass 35.5 u ?

Explanation

No, it is not possible. The fractional atomic mass of an element is its average mass and not the actual mass. In the case, the element chlorine exists as two isotopes with atomic mass 35 u and 37 u respectively in the ratio 3 : 1. The average come out to be fractional i.e., 35.5 u.