Multiple choice

The atomic number of an element is equal to the

  1. number of neutrons in its nucleus

  2. number of protons in its nucleus

  3. relative atomic mass

  4. number of electrons in its outermost orbit

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The atomic number is defined as the number of protons in the nucleus of an atom, which uniquely identifies the element.