1. During combustion, methane yields carbon dioxide and water. The unbalanced equation for
this reaction is:
CH4(g) + O2(g)
CO2(g) + H2O(l)
What will the mole ratios for the balanced equation be? (What coefficients are needed in order to
balance this equation?)
A. 1 : 2 : 1 : 2
B. 1 : 1 : 1 : 2
C. 1 : 1 : 2 : 1
D. 5 : 4 : 3 : 6
2. The balanced chemical equation for the combustion of butane (C4H10) is:
A. 2C4H10 + 13O2 8CO2 + 10H2O
B. 2CH4 + 5O2 2CO2 + 4H2O
C. 2C2H2 + 5O2
D. C4H10 + 12O2
CO2 + 2H2O
4CO2 + 5H2O
3. Consider the following reaction:
Mg + 2H2O
Mg(OH)2 + H2
H = -353 kJ
This reaction is
A. endothermic because heat is absorbed.
B. exothermic because heat is absorbed.
C. endothermic because heat is released.
D. exothermic because heat is released.
4. Which of the following sets of coefficients correctly balances the following chemical
equation?
Fe +
A. 2; 2; 2
B. 2; 3; 2
Cl2
FeCl3
C. 1; 1; 1
D. 1; 3; 1
5. Which of the following general equations represents a synthesis reaction?
A. A + B
AB
B. AX + B
C. AX + BZ
D. AB
A + BX
AZ + BX
A+B
6. What coefficients must be used to balance the following decomposition reaction?
KClO3
KCl + O2
A. 1; 1; 3
B. 1; 1; 2
C. 2; 2; 3
D. 3; 1; 2
7. Almost all chemical reactions absorb or release heat. This is because
A.
B.
C.
D.
phase changes always occur during chemical reactions.
energy is gained and lost as chemical bonds are broken and formed.
matter is gained and lost during chemical reactions.
chemical changes only occur when heat is added.
8. Consider the following reaction:
energy + 2 HgO (s)
This reaction is
A. an endothermic reaction.
B. an exothermic reaction.
2 Hg (l) + O2 (g)
C. a single-replacement reaction.
D. a synthesis reaction.
9. Aluminum (Al) combines with silver sulfide (Ag2S) to form aluminum sulfide (Al2S3) and
silver (Ag) during a single replacement reaction.
Which of the following shows the balanced chemical equation for this reaction?
A. Al + 2 Ag2S
2 Al2S3 + 2 Ag
B. 2 Al + 2 Ag2S
2 Al2S3 + 4 Ag
C. 2 Al + 3 Ag2S
Al2S3 + 6 Ag
D. 2 Al + 3 Ag2S
Al2S3 + Ag
10. What type of reaction is shown below?
Mg + S
MgS
A. synthesis
B. single replacement
C. decomposition
D. double replacement
11. An arrangement of chemical formulas and symbols that represent a complete chemical
reaction is called
A. a chemical symbol.
B. a chemical equation.
C. the products of a reaction.
D. an observation.
12. Two chemical reactions are shown below. We know that a chemical change takes place in
each of these reactions because new compounds are formed from the reactant materials.
2H2 (g) +O2 (g) → 2H2O (g)
H2 (g) + I2 (g) → 2HI (g)
H = -483.6 kJ
H = +53.0 kJ
What can be inferred from these reactions?
A. Formation of water from hydrogen and oxygen is endothermic.
B. Iodine is more reactive than oxygen.
C. Chemical changes can be endothermic or exothermic.
D. Chemical changes are always spontaneous.
13. What type of reaction is represented by the chemical equation shown below?
2 PbO2
2 PbO + O2
A. double-replacement
B. single-replacement
C. synthesis
D. decomposition
14. What is the general equation for a decomposition reaction?
A.
B.
C.
D.
A+B
A + BC
AB
AC + BD
AB
AC + B
A+B
AD + BC
15. When an elemental metal combines with an elemental nonmetal, it forms a:
A. covalent compound
B. polar covalent compound
C. binary ionic compound
D. double salt
16. What is the general equation for a single replacement reaction?
A.
B.
C.
D.
AB
AC + BD
A + BC
A+B
A+B
AD + BC
AC + B
AB
17. What type of reaction is represented by the chemical equation shown below?
AgNO3 + KCl
AgCl + KNO3
A. single-replacement
B. decomposition
C. double-replacement
D. synthesis
18. Which of the following sets of coefficients correctly balances the following chemical
equation?
Al(OH)3
Al2O3 +
H2O
A. 1; 1; 3
B. 2; 1; 2
C. 2; 1; 3
D. 3; 1; 2
19. Calcium carbonate can be used medicinally in vitamins as a calcium supplement or as an
antacid. It is formed by bubbling carbon dioxide gas (CO2) through a solution of calcium
hydroxide, Ca(OH)2. In addition to calcium carbonate (CaCO3), this reaction also produces water
(H2O).
Which of the following equations shows the correct balanced equation for this reaction?
A. 2 Ca(OH)2 + 2 CO2 → 2 CaCO3 + H2O
B. CaOH2 + CO2 → CaCO3 + H2O
C. Ca(OH)2 + CO2 → CaCO3 + 2 H2O
D. Ca(OH)2 + CO2 → CaCO3 + H2O
20. An endothermic chemical reaction
A. absorbs heat energy.
B. releases heat energy.
C. creates heat energy.
D. destroys heat energy.
21. Identify which of the following reactions is/are (a) combustion reaction(s).
1. CH4 + 2O2
CO2 + 2H2O
2. 2Mg + O2
2MgO
3. 2Na + Cl2
2NaCl
A. Only reaction 2 is an example of combustion reaction.
B. Only reaction 3 is an example of combustion reaction.
C. Only reaction 1 is an example of a combustion reaction.
D. Reactions 1 and 2 are examples of combustion reactions.
22. What is the general equation for a double-replacement reaction?
A.
B.
C.
A + BC
AB
AC + BD
AC + B
A+B
AD + BC
D.
A+B
AB
23. What type of reaction is represented by the chemical equation shown below?
2 K + MgBr2
2 KBr + Mg
A. single replacement
B. decomposition
C. synthesis
D. double replacement
24. Consider the following reaction:
CO2 + 2H2O
CH4 + 2O2
H = +802 kJ
This reaction is
exothermic because 802 kJ of heat energy have been released.
A.
B.
C.
D.
endothermic because 802 kJ of heat energy have been released.
exothermic because 802 kJ of heat energy have been absorbed.
endothermic because 802 kJ of heat energy have been absorbed.
25. An exothermic chemical reaction
A. destroys heat energy.
B. absorbs heat energy.
C. releases heat energy.
D. creates heat energy.
26. What coefficients must be used to balance the following synthesis reaction?
Li + S
Li2S
A. 3; 1; 2
B. 1; 1; 3
C. 2; 1; 1
D. 1; 1; 2
27. Potassium iodide (KI) combines with mercury chloride (HgCl2) to form potassium chloride
(KCl) and mercury iodide (HgI2) during a double replacement reaction.
Which of the following shows the balanced chemical equation for this reaction?
A.
B.
C.
D.
2 KI + HgCl2
KI + HgCl2
KCl + 2 HgI2
2 KCl + HgI2
KI + 2 HgCl2
KCl + 2 HgI2
2 KI + HgCl2
2 KCl + HgI2
28. Solid potassium chlorate decomposes into solid potassium chloride and oxygen gas
according to the following unbalanced equation:
KClO3 (s)
KCl (s) + O2 (g)
What mole ratios will balance this chemical equation?
A. 2 : 2 : 3
B. 2 : 2 : 2
C. 1 : 1 : 3
D. 1 : 1 : 2
Answers
1. A
2. A
3. D
4. B
5. A
6. C
7. B
8. A
9. C
10. A
11. B
12. C
13. D
14. C
15. C
16. C
17. C
18. C
19. D
20. A
21. D
22. C
23. A
24. D
25. C
26. C
27. D
28. A