II. Multiple Choice. Write the capital letter of the correct answer.
1. What can you find at the nucleus of an atom?
A. electron and proton
C. neutron and proton
B. electron and neutron
D. electron, proton and neutron
2. The electrons are
A. neutral in charge
C. moving around the nucleus
B. found always with proton
D. not involved in the reaction of atoms
3. A neutral sodium has 11 protons. How many electrons does it contain?
A. 10 B. 11
C. 12 D. 23
4. A neutral atom has an atomic number of 5 and mass number of 11. How many neutrons does it contain?
A. 4 B. 5
C.6 D. 11
5. How will you determine the mass number of an atom?
A. same with electron
C. electron + proton
B. same with proton
D. proton + neutron​