In which of the following sets do all species have the same number of electrons
a.) i-, xe, ba2+
b.) c, n3-, o2-
c.) sr2+, ba2+, ra2+
d.) s, s2-, s2+

Option a

Explanation:

a)

Atomic number of I = 53

No. of electrons = atomic number + no. of negative charge

                           = 53 + 1 = 54

Xe

Atomic number of Xe = 54

In a neutral atom, no. of electron is equal to no. of protons.

So. no. of electron in Xe = 54

a)

Atomic number of I = 56

No. of electrons = atomic number - no. of positive charge

                           = 56 - 2 = 54

All the species in the set a have 54 electrons.

it is the most commonly accepted one