Focus On Physical Science: California Grade 8

Chapter 8: Chemical Reactions

Standard Assessment

1.
What is the correct number to write in front of mercury(II) oxide (HgO) in the following equation: HgO ? 2Hg + O2? 5.b
A)1
B)2
C)4
D)3
2.
In a chemical equation for an endothermic reaction, how is the energy requirement indicated? 5.c
A)A letter E appears in boldface type over the arrow.
B)The word energy is written as a product.
C)The word energy is written as a reactant.
D)A Greek letter, gamma, is drawn over the arrow.
3.
What is not a physical property of paper? 7.c
A)It's flat.
B)It's white.
C)It's smooth.
D)It burns.
4.
Which reactant correctly balances the following equation: 4Al + __________ ? 2Al2O3? 5.b
A)2O2
B)O3
C)3O
D)3O2
5.
An example of a physical property is __________. 7.c
A)acidic
B)flammability
C)color
D)ability to rust
6.
When you observe a chemical property, the substance __________. 7.c
A)remains the same
B)changes
C)melts
D)burns
7.
As a result of the experiments of Lavoisier, you know that in a chemical reaction, the mass of the products __________. 5.b
A)always equals the mass of the reactants
B)is twice as great as the mass of the reactants
C)is less than the mass of the reactants
D)cannot be predicted based on the mass of the reactants
8.
__________ reactions absorb heat energy. 5.c
A)Endothermic
B)Exothermic
C)Inhibited
D)Catalyzed
9.
When sandpaper smooths a piece of wood, this is an example of a __________. 7.c
A)change of matter
B)chemical change
C)change of state
D)physical change
10.
New substances produced by a chemical reaction are __________ . 5.b
A)reactants
B)resultants
C)products
D)coefficients
11.
An example of a chemical property is __________. 7.c
A)color
B)ability to burn
C)mass
D)density
12.
Color and shape describe the __________ of matter. 7.c
A)feel
B)chemical properties
C)chemistry
D)appearance
13.
The law of conservation of mass states that __________ . 5.b
A)matter can be created and destroyed but does not change forms
B)in a chemical reaction, matter is not created or destroyed, but is conserved
C)in a chemical reaction, efforts should be made to preserve rare elements without changing them
D)in a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants
14.
__________ reactions release heat energy. 5.c
A)Exothermic
B)Endothermic
C)Catalyzed
D)Inhibited
15.
During a chemical change, a substance __________. 7.c
A)loses chemical properties
B)remains the same
C)changes into another substance
D)changes into another substance
16.
When you observe a physical property, the substance __________. 7.c
A)melts
B)changes
C)burns
D)does not change
17.
In chemical equations, __________ represent the number of units of each substance. 5.b
A)products
B)reactants
C)numbers in front of the chemical formulas
D)precipitates
18.
Hg is the symbol for __________. 5.b
A)helium
B)mercury
C)hydrogen
D)silver
19.
__________ is a way to describe a chemical reaction using chemical formulas and symbols. 5.b
A)A chemical equation
B)Synthesis
C)A physical law
D)The law of conservation of matter
20.
In the formula H2O, what does the number 2 indicate? 3.b
A)Each hydrogen atom gains two electrons from the oxygen atom.
B)Each hydrogen atom loses two electrons to the oxygen atom.
C)There are two atoms of hydrogen in this molecule.
D)Two atoms each of hydrogen and oxygen are in this molecule.
Grade 8
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