How many protons, electrons and neutrons are present in an atom of potassium with a mass number of 39. ..?

How many protons, electrons and neutrons are present in an atom of potassium with a mass number of 39 and charge of +1?

19 protons, 19 neutrons, 19 electrons
19 protons, 20 neutrons, 18 electrons
19 protons, 39 neutrons, 19 electrons
39 protons, 18 neutrons, 18 electrons
5 answers 5