Give the number of electrons in the species and
A positive charged ion denotes the loss of an electron & A negative charged ion represents the gain of an electron by a species.
For H+2:
Number of electrons present in Hydrogen molecule = 2
So, Number of electrons present in H+2 = 2 – 1
= 1
For H2:
Number of electrons present in Hydrogen molecule = 2
For O+2:
Number of electrons present in Oxygen molecule = 8 + 8
= 16
So, Number of electrons present in O+2 = 16 - 1
= 15