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15. The number of atoms in exactly 12.00 g of C-12 is called 25. When carbon burns with an insufficient supply of oxygen,
a. atomic number. carbon monoxide is formed according to the following
b. atomic weight. equation: 2 C + O 2 2 CO. What category of chemical
c. Avogadro’s number. reaction is this?
d. molecular number. a. Combination
16. Any substance that contains Avogadro’s number of particles is b. Ion exchange
called a (an) c. Replacement
a. mole. d. None of the above is correct because the reaction is
b. atomic number. incomplete.
c. gopher. 26. According to the activity series for metals, adding metallic iron
d. pound. to a solution of aluminum chloride should result in
17. A material that speeds up a chemical reaction without being a. a solution of iron chloride and metallic aluminum.
permanently changed by the reaction is a (an) b. a mixed solution of iron and aluminum chloride.
a. catalyst. c. the formation of iron hydroxide with hydrogen given off.
b. reactant. d. no metal replacement reaction.
c. product. 27. In a replacement reaction, elements that have the greatest ability
d. active metal. to hold onto their electrons are
18. The most active metals are found in group a. the most chemically active.
a. IA. b. the least chemically active.
b. IIA. c. not generally involved in replacement reactions.
c. IB. d. None of the above is correct.
d. IIB. 28. Of the following elements, the one with the greatest electron-
19. Potassium reacts with water to form potassium hydroxide and holding ability is
hydrogen gas. What kind of reaction is this? a. sodium.
a. Decomposition b. zinc.
b. Combination c. copper.
c. Replacement d. platinum.
d. Ion exchange 29. Of the following elements, the one with the greatest chemical
20. The molecular weight of sulfuric acid, H 2 SO 4 , is activity is
a. 49 u. a. aluminum.
b. 50 u. b. zinc.
c. 98 u. c. iron.
d. 194 u. d. mercury.
21. A balanced chemical equation has 30. You know that an expected ion exchange reaction has taken place
a. the same number of molecules on both sides of the if the products include
equation. a. a precipitate.
b. the same kinds of molecules on both sides of the equation. b. a gas.
c. the same number of each kind of atom on both sides of the c. water.
equation. d. any of the above.
d. all of the above. 31. The incomplete equation of 2 KClO 3 (s) probably represents
22. The law of conservation of mass means that which type of chemical reaction?
a. atoms are not lost or destroyed in a chemical reaction. a. Combination
b. the mass of a newly formed compound cannot be changed. b. Decomposition
c. in burning, part of the mass must be converted into fire in c. Replacement
order for mass to be conserved. d. Ion exchange
d. molecules cannot be broken apart because this would result 32. In the equation 2 H 2 (g) + O 2 (g) 2 H 2 O(1)
in less mass. a. the total mass of the gaseous reactants is less than the total
23. A chemical equation is balanced by changing mass of the liquid product.
a. subscripts. b. the total number of molecules in the reactants is equal to the
b. superscripts. total number of molecules in the products.
c. coefficients. c. one volume of oxygen combines with two volumes of
d. Any of the above is correct as necessary to achieve a balance. hydrogen to produce two volumes of water.
d. All of the above are correct.
24. Since wood is composed of carbohydrates, you should expect
23
which gases to exhaust from a fireplace when complete 33. If you have 6.02 × 10 atoms of metallic iron, you will have how
combustion takes place? many grams of iron?
a. Carbon dioxide, carbon monoxide, and pollutants a. 26
b. Carbon dioxide and water vapor b. 55.85
c. Carbon monoxide and smoke c. 334.8
d. It depends on the type of wood being burned. d. 3.4 × 10 25

270 CHAPTER 10 Chemical Reactions 10-20