Write the electronic configuration of any one pair of isotopes and isobars.

Explanation

(a) A pair of isotopes of chlorine is `._(17)^(35)Cl and ._(17)^(37)Cl`. The atomic number of both the isotopes is the same, 17. So, the electronic configuration of both these isotopes will be 2,8,7
(b) A pair of isobars is `._(18)^(40)Ar and ._(20)^(40)Ca`. The atomic number of argon (Ar) is 18, so its electronic configuration will be 2,8,8. The atomic number of calcium (Ca) is 20, so its electronic configuration will be 2,8,8,2.