Question

Plzz. answer the question ​

Answer 1

Chlorine always has an atomic mass 35.5 amu because chlorine has two isotopes Cl-35 and Cl-37 and their abundance is 75% and 35% respectively . Therefore the average mass of Cl 35 and Cl 37 is calculated as 35.5 u

Answer 2

this is because of the existence of its isotopes. it is found in form of chlorine- 35 and chlorine- 37. so the average of both masses is taken to arrive at the relative atomic mass. and hence the relative atomic mass is always 35.5