Phosphorus has three isotopes, 31p, 32p, and 33p. the atomic number of phosphorus is 15. how many protons does each of the isotopes have

For isotopes of any element, the number of protons remains the same, BUT the number of neutrons changes. Since each of the isotopes listed is phosphorus, All three have 15 protons. (They have 16, 17 and 18 protons respectively.)