Question

Composition of the nuclei of two atomic species X and Y are given as under 

                       X           Y 

Protons =        6           6 

Neutrons =      6           8 

Give the mass numbers of X and Y. What is the relation between the two species? 

Answer 1

Mass number of X  = Number of protons + Number of neutrons 

                                = 6 + 6 

                                = 12 

Mass number of Y = Number of protons + Number of neutrons 

                              = 6 + 8 

                              = 14 

These two atomic species X and Y have the same atomic number, but different mass numbers. Hence, they are isotopes.