Question

which of the following determines the identity of an element? *
number of protons
atomic mass
number of neutrons
number of energy levels

Explanation:

The number of protons in an atom's nucleus, known as the atomic number, uniquely identifies an element. Different elements have different atomic numbers. Atomic mass can vary (isotopes), number of neutrons can vary (isotopes), and number of energy levels relates more to electron configuration and period in the periodic table rather than element identity.

Answer:

number of protons