The helium atom has 2 protons, 2 electrons and 2 neutrons.
What is its atomic number

Its atomic number is 2, so it has two protons in its nucleus. Its nucleus also contains two neutrons. Since 2 + 2 = 4, we know that the mass number of the helium atom is 4. Finally, the helium atom also contains two electrons since the number of electrons must equal the number of protons.

Explanation:

Brainliest Please???

there are two significant figures.