Which pair of neutrons and protons correspond to the isobars of Ar and Ca, which have a mass number of 40?

Question

Quizplus · Accepted Answer

Isobars are atoms of different elements (thus different numbers of protons) with the same mass number. The mass number is the sum of protons and neutrons. For Ar (argon) and Ca (calcium) to be isobars with a mass number of 40, Ar must have 18 protons (since it's atomic number 18) and 22 neutrons (40 - 18 = 22), and Ca must have 20 protons (since it's atomic number 20) and 20 neutrons (40 - 20 = 20).

Which Pair of Neutrons and Protons Correspond to the Isobars