1. A 0.321-g sample of aluminum is reacted with 1.000 g of solid sulfur to produce a specific aluminum-sulfide compound. After the reaction, all of the aluminum is used and the mass of un-reacted sulfur is 0.430 g. What is the mass of the compound produced?

2. A 0.847 g sample of nickel reacts with chlorine producing 1.870 g nickel(II) chloride as the only product. Using the law of constant composition, determine the mass of nickel contained in a 5.054 g sample of nickel(II) chloride.

3. The element "X" forms two compounds with element "Y". In the first compound, 1.000 g X is combined with 0.406 g Y. In the second compound, 2.000 g X reacts with 1.218 g Y. Show that these results are consistent with Dalton's law of multiple proportions.

4. For the following isotopes, write their symbols in the form _Z^AE

a. arsenic-75
b. gold-197

5. Indicate the number of protons, neutrons, and electrons in each of the following atoms:

a. tin-119
b. calcium-40

6. Indicate the number of protons, neutrons, and electrons in each of the following atoms:

a. ¹³¹Xe
b. ⁹³Nb

7. Indicate the number of protons, neutrons, and electrons in each of the following ions:

a. 56Fe³⁺
b. 133Cs¹⁺

8. Indicate the number of protons, neutrons, and electrons in each of the following ions:

a. ⁸⁰Br^-
b. ³²S^2-

9. The masses and percent abundances of the four un-naturally occurring isotopes of the imaginary element notrealium are ⁷¹Nt, 70.2737 u, 17.054%; ⁷³Nt, 72.2532 u, 24.531%; ⁷⁷Nt, 76.2123 u, 13.067%; and ⁷⁴Nt, 73.2430 u, 45.348%. Calculate the weighted-average atomic
mass of notrealium in atomic mass units, u.