Isotopes of an element have

Isotopes of an element have

  1. the same number of protons and neutrons.
  2. the same number of protons and electrons.
  3. the same number of neutrons and electrons.
  4. the same number of protons but different numbers of neutrons. ✓

Explanation

Isotopes are atoms of one element with different masses. Same protons means same element. Different neutrons means different mass.

Carbon-12 and Carbon-14 are isotopes. Both have 6 protons. One has 6 neutrons, the other has 8 neutrons.

Remember: Proton number defines the element. Neutron number creates isotopes.