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

(a) Isotopes: Isotopes are atoms which have the same number of protons but different number of neutrons. They have same atomic number but different mass number.

Example: Carbon molecule exists as ₆C¹² and ₆C¹⁴ but when their electronic configuration is K-2; L-4

(b) Isobars: Isobars are atoms which have the same mass number but different atomic number.

Example: Electronic configuration of ₂₀Ca⁴⁰is – K-2; L-8; M-8; N- 2 and of ₁₈Ar⁴⁰ is – K-2; L-8; M-8