Unit 3 Self-Quiz, pages 354–355
1. (a)
2. (d)
3. (a)
4. (b)
5. (b)
6. (b)
7. (d)
8. (d)
9. (b)
10. (a)
11. (d)
12. (c)
13. (c)
14. (d)
15. (d)
16. (d)
17. True
18. False. The measurement of the mass of a particular gas in the air is an example of
quantitative analysis. /U
19. False. A mole is defined as the number of atoms equal to the molar mass of the chemical
substance.
20. True
21. True
22. False. To find the number of entities when given the amount of a substance, multiply the
amount by Avogadro’s constant.
23. False. The subscripts in the formula H2O represent the ratio in which atoms of hydrogen and
oxygen combine.
24. True
25. False. Percentage composition is the percentage by mass of each element in a compound.
26. True
27. True
28. False. In examining simulated British banknotes for the presence of cocaine, scientists used
thermal desorption to lift materials from the surface of the test strips.
29. True
30. False. A molecular formula represents the numbers of combining atoms in a compound’s
molecules. Or An empirical formula represents the simplest ratio of combining atoms in a
compound’s molecules.
31. True
32. True
33. False. When a reaction has gone to completion, any remaining starting material comes from
the excess reactant.
34. False. The ratio used to convert amount of product to mass has units of g/mol.
Copyright © 2011 Nelson Education Ltd.
Unit 3: Quantities in Chemical Reactions
U3-3
35. False. The formula for calculating percentage yield is:
actual yield
! 100 %
theoretical yield
Copyright © 2011 Nelson Education Ltd.
Unit 3: Quantities in Chemical Reactions
U3-4