Question 40 (1 point) The average atomic mass, sometimes called the mass number is determined by which of the following?
a
Ob
number of protons only
number of neutrons only
number of protons and neutrons
number of neutrons and electrons
Ос
Od
HELP ASAP

It is the number of protons and neutrons.

Explanation:

For any given isotope, the sum of the numbers of protons and neutrons in the nucleus is called the mass number. This is because each proton and each neutron weigh one atomic mass unit (amu). By adding together the number of protons and neutrons and multiplying by 1 amu, you can calculate the mass of the atom.