Which of the following is an isoelectronic pair?a) H-, He+b) Na, Mg2+c) Cl-, Ned) Li, Be+

a) H^-  number of electrons =  2
He⁺ number of electrons = 1

b) Na number of electrons =  11
Mg²⁺ number of electrons = 10

c) Cl^- number of electrons = 18
Ne number of electrons = 10

d) Li number of electrons = 3
Be⁺ number of electrons = 3

Hence (d) has isoelectronic pair that is same number of electrons.