10. In which of the following is the symbol for the ion and the total number of electrons it contains given correctly? A Al3+ has 16 electrons
B S2- has 2 electrons
C Br1- has 34 electrons
D Ca2+ has 18 electrons

9. Which total mass is the smallest?
A The mass of 2 electrons
B The mass of 2 neutrons
C The mass of 1 electron plus the mass of 1 proton
D The mass of 1 neutron plus the mass of 1 electron

8. After measuring the ratio of the charge of a cathode ray particle to its mass, Thomson concluded that the particles
A Had no mass
B Had a very small mass
C Had a very large mass
D Carried a positive charge