The atomic number of an element is equal to the number of contained in one atom of that element. protons neutrons electrons protons and neutrons the atomic number of an element is equal to the number of protons contained in one atom of that element.

Option (a) is the correct answer.

Explanation:

The nucleus of an atom consists of protons and neutrons. Protons are positively charged species whereas neutrons do not have any charge.

For example, the atomic number of sodium is 11. This means there are 11 protons. Whereas the mass number of sodium is 23, that is, mass number means number of protons + number of neutrons.

The number of protons in an atom displays the atomic number of the respective atom.

Thus, we can conclude that the atomic number of an element is equal to the number of protons contained in one atom of that element.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.