okay another question from my test I’m almost done sorry for spamming I just gave up on that class because I’m pretty sure it can’t get worst :D

The Answer is C.

Explanation:

The Mass number is the total number of nuetrons and protons in the nuclues. So there are 84 particles in the nuclues because the mass number is 84. Also because the atomic number is 36 that means that there are 36 protons. It also happens to mean that there are 36 electrons because the amount of the protons is equal to electrons unless stated otherwise. Because electrons reside outside of the nuclues there are 36 particles outside the nueclues.