Question

what will be the number of neutrons if atomic number is 15 and mass number is 31

Answer 1

Answer:

16 neutrons

This is the isotope phosphorus-31. It has 15 protons, 15 electrons, and 16 neutrons

Answer 2

Explanation:

Neutrons + proton = mass no.

atomic no. = no. of protons

so, protons = 15

Neutrons = mass no. - protons

neutrons = 31-15

neutrons = 16