Question

atomic number and mass number of phosphorus is 15 and 31 reduce the number of neutrons present in the nucleus

Answer 1

Isotopes are named for their mass numbers and known for element that has 15 protons. It increase atomic numbers by taking 15 electrons and 16 neutrons used for mass numeric minus atomic numbers.

This isotope is phosphorus 31 and atomic number is 15 only.

Potassium has mass number of 39 and atomic range is 19.