The isotopes of chlorine with mass numbers 35 and 37 exist in the ratio of

Chlorine occurs in nature in two isotopes forms of masses 35 u and 37 u in the ratio of 3:1 respectively. What is the average atomic mass of the Chlorine atom ?

The mass number of chlorine is

Two types of atoms of chlorine have atomic masses 35 and 37, then why is the atomic mass of chlorine taken as 35.5?

The two isotopes of chlorine have atomic mass 35 u and 37 u. Should they be placed in separate slots in the periodic table ?