An oxide ion, O2- has the same electrons configuration as an atom of which noble gas?

NYC Regents Chemistry Exam Jan 2023

40. An oxide ion, O2- has the same electrons configuration as an atom of which noble gas?

1. Helium

2. Neon

3. Argon

4. Krypton

Solution: O^2- has 2 extra electrons. Looking on the Periodic Table oxygen has an atomic number of 8 which means it has 8 electrons when neutral. 8+2= 10 electrons for oxygen 2- ion. Neon has an atomic number of 10 and 10 electrons when neural. Choice 2 is correct.