Question

What is the mass number of an ion with 105 electrons, 158 neutrons, and a +1 charge?

Answer 1

It has 105 electrons and a +1 charge. Therefore, it must have 106 protons in its nucleus.

Explanation:

So, by definition, your unknown compound has `Z` (the atomic number) = 106. That is something transuranic, which you will have to look up on your Periodic Table! Would you report the result back here?

Note that the quoted number of neutrons is simply a distractor here!