Answer
a. atomic number
b. atomic number and mass number
c. mass number
d. atomic number
Work Step by Step
a. the atomic number gives the number of protons in an atom
b. the mass number is the number of protons (atomic number) + number of neutrons
c. the mass number is number of protons + number of neutrons, which are the particles inside the nucleus
d. the number of protons is the same as electrons, but with opposite charges, that's why we can use the atomic number to determine the number of electrons
You can find this answer at page 113, topic 'The Mass of the Atom'
