We didn't get to go over the rest of the package in class. Here are the answers to the rest of the questions.
1. Atomic mass is a weighted average based upon the different isotope masses and their relative abundance.
5. No, the atomic number is equal to the number of protons, which is equal for isotopes.
6. Yes, mass number is equal to the total number of neutrons and protons. Since isotopes have equal numbers of protons but different number of neutrons.
1a. 27 a.m.u.
b. aluminum, Al
2a. 24, 25, 26
b. 24.32 amu
c. magnesium, Mg
3a. 50, 52, 53, 54
b. 52.1 amu
c. chromium, Cr