How many neutrons are in a nucleus that has 45 protons and a mass number of 160?

1 Answer


I think the nucleus contains 95 neutrons.


I think you made a typo in your question.

The nucleus is more likely to have 65 protons.

The mass number means the number of protons #+# neutrons an ion, isotope, or atom has.

So, if we already know the number of protons, which is the same as its atomic number, we can find the neutrons.

For this problem, we know that the number of protons is #65#, and the mass number is #160#.

To find the neutrons, we do this:

#"mass number - protons = 160 - 65 = 95"#