Georgia Science Grade 8

Chapter 7: Chemical Reactions

CRCT Practice

1
The photograph shows the reaction of copper (Cu) with silver nitrate (AgNO3) to produce copper nitrate (Cu(NO3)2) and silver (Ag). The chemical equation that describes this reaction is the following: 2AgNO3 + Cu → Cu(NO3)2 + 2Ag. What term describes what is happening in the reaction?

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A)catalyst
B)chemical change
C)inhibitor
D)physical change
2
Which term describes the copper on the left side of the equation?

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A)reactant
B)catalyst
C)enzyme
D)product
3
The illustration shows a demonstration of electrolysis, in which water is broken down into hydrogen and oxygen. Which is the best way to write the chemical equation for this process?

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A)H2O + energy → H2 + O2
B)H2O + energy → 2H2 + O2
C)2H2O + energy → 2H2 + O2
D)2H2O + energy → 2H2 + 2O2
4
For each atom of hydrogen that is present before the reaction begins, how many atoms of hydrogen are present after the reaction?

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A)1
B)2
C)4
D)8
5
Which term best describes a chemical reaction that absorbs heat energy?
A)catalytic
B)exothermic
C)endothermic
D)acidic
6
What should be balanced in a chemical equation?
A)electrons
B)atoms
C)molecules
D)molecules and atoms
7
What is the purpose of an inhibitor in a chemical reaction?
A)to decrease the shelf life of food
B)to increase the surface area
C)to decrease the speed of a chemical reaction
D)to increase the speed of a chemical reaction
8
When solutions of calcium chloride (CaCl2) and silver nitrate (AgNO3) are mixed, calcium nitrate (Ca(NO3)2) and a white precipitate, or residue, form. What is the chemical formula of the precipitate?

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A)AgCl
B)Ag2C1
C)AgCl2
D)Ag2Cl3
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