Answer:
3. The total number of protons and neutrons in an atom is its mass number.
4. The mass number of a helium atom with 2 protons and 2 neutrons is 4.
5. A beryllium atom with 4 protons and a mass number of 9 has 5 neutrons.
6. The chemical symbol is Ne. The atomic number is 10. The mass number is 22.
7. Neon-22
8. Not enough information
