7. What is the formula weight of calcium carbonate, CaCO₃?
     a.  188.11 g/mol         b.  175.33 g/mol            c.  201.32 g/mol         d.  100.09 g/mol
  8. The mass of 0.75 moles of Al₂(SO₄)₃ is approximately
     a.  257 g.         b.  154 g.         c.  650 g.         d.  332 g.
  9. Calculate the number of molecules in 1.00 gram of water.
     a.  6.02 x 10²³ molecules         b.  4.76 x 10²³ molecules
     c.  2.14 x 10²¹ molecules         d.  3.34 x 10²² molecules
 10. What is the percent oxygen in calcium thiosulfate (CaS₂O₃)?
       The formula weight of calcium thiosulfate is 152.22 g/mol.
     a.  23.0%         b.  31.5%         c.  39.3%         d.  43.5%
 11. Which of the following has the smallest percent oxygen by mass?
     a.  SO₂         b.  CO₂         c.  NO₂
 12. Upon combustion, a 5.645 g sample of an organic compound gave 19.083 g of CO₂;
       the percent by mass of carbon in the compound is
     a.  27.29 percent.          b.  29.58 percent.          c.  52.08 percent.          d.  92.25 percent.
 13. Which of the following has the largest empirical weight?
     a.  C₉H₁₂         b.  C₆H₁₄         c.  C₅H₁₂         d.  C₇H₁₄
 14. The composition of a certain compound is 67.2 percent Xe and 32.8 percent O;
       its empirical formula is
     a.  XeO.          b.  XeO₂.          c.  XeO₄.          d.  XeO₆.
 15. Which one of the following reactions (equations) is balanced?
     a.  C₂H₅OH + O₂ ---> H₂O + CO₂
     b.  C₂H₅OH + O₂ ---> 3 H₂O + 2 CO₂
     c.  C₂H₅OH + 3 O₂ ---> 3 H₂O + 2 CO₂
     d.  2 C₂H₅OH + 7 O₂ ---> 6 H₂O + 4 CO₂
 16. Aluminum is produced from the oxide according to the following equation:
           Al₂O₃(s) --->   ?   Al(s) + O₂(g).
      When this equation is balanced, the coefficient of the aluminum is
     a.  1.          b.  2.          c.  4.          d.  6.
 17. What is the sum of the coefficients in the balanced equation?
            KClO₃  +       C₁₂H₂₂O₁₁ --->         KCl  +         CO₂  +         H₂O
     a.  39         b.  40         c.  42         d.  45
 18. What is the coefficient of the NH₃ when the following equation is balanced?
           ?   NH₃ +  Cl₂  --->    N₂H₄  +  NH₄Cl
     a.  1         b.  2         c.  3         d.  4
 19. What is the sum of the coefficients for the combustion of C₃H₆?
     a.  23         b.  18         c.  25         d.  19
 20. The reaction N₂(g) + 2 O₂(g) ---> 2 NO₂(g) indicates that
     a.  one atom of nitrogen reacts with two atoms of oxygen.
     b.  one molecule of nitrogen reacts with two moles of oxygen.
     c.  one mole of nitrogen reacts with two moles of oxygen.
 21. How many moles of Cl₂ are required to react with 5.00 moles of CH₄?
       CH₄ + 2 Cl₂ -----> CH₂Cl₂ + 2 HCl
     a.  2.50 moles         b.  5.00 moles         c.  10.0 moles
 22. Magnesium metal reacts with nitrogen to produce magnesium nitride according to the
       following reaction:
       3 Mg(s) +      N₂(g) --->  Mg₃N₂(s).
      What mass of nitrogen is required to react with 5.00 moles of magnesium?
     a.  420. g         b.  163. g         c.  46.7 g         d.  24.3 g
 23. Ozone can be prepared from oxygen according to the following reaction.
        3 O₂(g) ---> 2 O₃(g)
      What mass of ozone can be prepared from the reaction of 50.00 grams of oxygen?
     a.  75.00 g         b.  33.33 g         c.  50.00 g         d.  100.00 g
 24. What mass of oxygen is required to completely combust 1.00 g of CH₄?
     a.  3.99 g         b.  2.99 g         c.  1.99 g         d.  0.99 g
 25. Consider the following equation:  3 X + 2 Y ---> Z.  If 1 mole of X and 1 mole of Y are mixed
       and allowed to react, which will be completely consumed in the reaction?
     a.  X         b.  Y