Question

If an atom has 42 protons and 36 neutrons, how many electrons will it have?

Answer 1

the quick answer is 42 electrons would be required however, the question has a kicker in it, there should be between 42 and 50 neutrons there also if the atom is to be stable. with a marginal number of neutrons like 36 atom will be highly unstable and most likely self distruct .

Answer 2

If an atom is in its natural state the number of protons will equal the number of electrons. This is because an atom naturally wants to be "even" and since protons have a positive charge, the atom will have the same number of electrons (negative) so that they cancel each other out.