Step-by-step explanation:
We have to find the overall charge of a substance that contains 15 protons, 18 electrons and 16 neutrons.
A proton is a subatomic particle that we can find in the nucleus of an atom. Its charge is +1.
An electron is a subatomic particle that we can find around the nucleus and its charge is opposite to the one of the proton. Its charge is -1.
A neutron is a subatomic particle that can be found in the nucleus and has no charge, so its charge is 0.
charge of p+ = +1 charge of n° = 0 charge of e- = -1
Our element has 15 protons, 18 electrons and 16 neutrons, the overall charge will be.
overall charge = 15 * (+1) + 18 * (-1) + 16 * (0)
overall charge = -3
Answer: d. -3