i) Isotopes: Chlorine has two isotopes \(_{35}^{17}HCl\) and \(_{37}^{17}HCl\).
Electronic configuration: Electronic configuration of two chlorine atoms is as follows:
ii) Isobars: Let us consider two elements - calcium atomic number 20, and argon, atomic number 18. The number of electrons in these atoms is different, but the mass number of both these elements is 40. They are differ in Electronic configuration.