Question

For an atom (which is neutral), which of these must be

true?
The number of protons is equal to the number of electrons
The atomic number is equal to the mass number
The number of electrons is equal to the number of neutrons
The number of protons is equal to the number of neutrons

Answer 1

The number of protons is equal to the number of electrons

Step-by-step explanation:

For an atom to be neutral, all the charges have to equal zero. Because protons are charged +1 and electrons are charged -1, the number of protons has to be equal to the number of electrons for the charges to cancel out.