We can represent atoms by listing the number of protons, neutrons, and electrons—for example, 2p+,2n0,2e− for helium. Which of the following represents the 18O isotope of oxygen? a. 7p+,2n0,9e− b. 8p+,10n0,8e− c. 9p+,9n0,9e− d. 10p+,8n0,9e-