The atomic number is the number of protons in an atom. How many protons does the element He have?

The number of protons in He is 2.

Explanation:

Atomic number refers to the number of protons in the nucleus of an atom.

He is a noble gas whose atomic number is 2.

Therefore, the number of protons in the nucleus of He is 2.

Also, the number of neutrons in the nucleus of He is 2

And mass number is the sum of protons and neutrons present in the nucleus of an atom.

Therefore, mass number of He = 2 + 2 = 4