6. What does the nucleus contain?
- Protons+neutons
- electrons+neutron
- electrons
- proton+electrons
7. What does the mass number represent?
- Total number of neutrons
- Total number of protons+neutrons
- Total number of protons+electrons
- Total number of electrons
8. What is the charge of an electron?
- no charge= neutral
- -1= negative
- +1= positive
