A substance has 15 protons,16 neutrons,and 15 electrons.Which isotope is it?
A)P-30
B)P-31
C)S-30
D)S-31

Question

Quizplus · Accepted Answer

The number of protons determines the atomic number, so this substance is a neutral atom of phosphorus (P) because it has 15 protons and 15 electrons. The total number of protons and neutrons is the atomic mass, so this atom has a mass of 31 (15 protons +16 neutrons). Therefore, the isotope is P-31. The other options, S-30 and S-31, are isotopes of sulfur (S) and do not fit the given information.

A Substance Has 15 Protons,16 Neutrons,and 15 Electrons