Indiana Science Grade 8

Chapter 7: Chemical Reactions

Standardized Test Practice

1.
The graph shows how the concentrations of two compounds change during a chemical reaction. During which time period does the product change most rapidly?

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A)0 min to 1 min
B)2 min to 3 min
C)1 min to 2 min
D)3 min to 4 min
2.
Look at the following equation:
2AgNO3 + Cu →Cu(NO3)2 + 2Ag
Which term describes the copper on the left side of the equation?
A)reactant
B)catalyst
C)enzyme
D)product
3.
Which particles must have an equal number on both sides of a chemical equation?
A)electrons
B)molecules
C)subscripts
D)atoms
4.
The illustration shows the breakdown of water when energy is added to it. What is the chemical equation for the reaction?

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A)H2O + energy → 2H + O
B)2H2O + energy → 2H2O + O2
C)H2O + energy → H2O + O2
D)2H2O + energy → 2H2 + 2O
5.
Which of the following terms best describes the reaction?

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A)acidic
B)catalytic
C)exothermic
D)endothermic
6.
What is the purpose of a catalyst in a reaction?
A)increase the concentration in a reaction
B)increase the speed of a chemical reaction
C)decrease the concentration in a reaction
D)decrease the speed of a chemical reaction
7.
Which of the following chemical equations is balanced?
A)2CF2Cl2 → 2CF2Cl + 2Cl2
B)C3H8 + 5O2 → 3CO2 + 4H2O
C)NaCl + H2SO4 → Na2SO4 + HCl
D)Zn + CrCl3 → CrCl2 + ZnCl2
8.
Look at the chemical equation below:
3Na + AlCl3 → 3NaCl + Al
If you start with 15 molecules of sodium, how many aluminum molecules will be produced?
A)3
B)5
C)10
D)15
9.
What effect does an increased concentration of reactant often have on chemical reactions?
A)increased rate
B)decreased rate
C)decreased temperature
D)increased temperature
10.
Which of the following is used to speed up reactions in the body's cells?
A)coefficient
B)inhibitor
C)precipitate
D)enzyme
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