Question

X and Y are two atomic species​

Answer 1

Explanation:

Atomic mass of X = Number of protons + Number of neutrons = 6 + 6 = 12. Atomic mass 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.