Question

the element are identified by their atomic number not by their mass number justify the statement​

Answer 1

Answer:

the elements of the new periodic table by Bohr ( designed by Henry Mosely) works on the principle that the elements are the periodic function of their atomic number. This is done because there is no problem of isotopes.

Answer 2

Answer:

however, the mass number of an element may vary, as different isotopes of a same element have different numbers of neutron for the same atomic number. They are both the same element i.e. but with different mass number. so the mass number alone cannot uniquely identify an element.