North Carolina Science Grade 8

Chapter 13: Chemical Reactions

Section 1 Self-Check Quiz-Eng.

1.
A change in which one or more substances are converted into new substances is a __________ .
A)physical change
B)nuclear reaction
C)chemical change
D)chemical fusion
2.
New substances produced by a chemical reaction are __________ .
A)resultants
B)reactants
C)products
D)coefficients
3.
__________ is a way to describe a chemical reaction using chemical formulas and symbols.
A)Synthesis
B)A physical law
C)The law of conservation of matter
D)A chemical equation
4.
As a result of the experiments of Lavoisier, you know that in a chemical reaction, the mass of the products __________.
A)is twice as great as the mass of the reactants
B)always equals 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
5.
The chemical formula for a compound tells __________ .
A)how stable the compound is
B)what type of chemical bond it forms
C)what elements it contains
D)how electrons are arranged
6.
The law of conservation of mass states that __________ .
A)matter can be created and destroyed but does not change forms
B)in a chemical reaction, efforts should be made to preserve rare elements without changing them
C)in a chemical reaction, matter is not created or destroyed, but is conserved
D)in a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants
7.
In chemical equations, __________ represent the number of units of each substance.
A)numbers in front of the chemical formulas
B)reactants
C)products
D)precipitates
8.
Which reactant correctly balances the following equation: 4Al + __________ → 2Al2O3?
A)3O2
B)O3
C)3O
D)2O2
9.
What is the correct number to write in front of mercury(II) oxide (HgO) in the following equation: HgO → 2Hg + O2?
A)1
B)4
C)2
D)3
10.
Which of the following symbols in a chemical equation means "produces"?
A)
B)+
C)[p]
D)(aq)
11.
Why is oxygen written with a subscript 2 in CO2?
A)Its mass is twice as great as the reactants'.
B)Carbon always bonds to two oxygen atoms.
C)Each molecule of carbon dioxide has two oxygen atoms.
D)Its mass increases by two times as a result of the reaction.
12.
What does it mean for a chemical equation to be balanced?
A)The solid products weigh the same as the reactants.
B)The reactants and the products are written with the same coefficients.
C)There are the same number of atoms of each element on both sides of the equation.
D)The number of reactants is equal to the number of products.
13.
A(n) __________ is a substance that speeds up a chemical reaction without being permanently changed itself.
A)inhibitor
B)exotherm
C)catalyst
D)endotherm
14.
Which of the following statements about energy-releasing reactions is true?
A)The products are more stable.
B)The products are less stable.
C)The bonds of the products have more energy than those of the reactants.
D)The energy released is always in the form of heat.
15.
Which of the following statements about energy-absorbing reactions is true?
A)The reactants are less stable.
B)The bonds of the reactants have more energy than those of the products.
C)The energy supplied is always in the form of electricity.
D)The reactants are more stable.
16.
__________ reactions release heat energy.
A)Endothermic
B)Catalyzed
C)Exothermic
D)Inhibited
17.
__________ reactions absorb heat energy.
A)Exothermic
B)Endothermic
C)Inhibited
D)Catalyzed
18.
In a chemical equation for an endothermic reaction, how is the energy requirement indicated?
A)The word energy is written as a product.
B)The word energy is written as a reactant.
C)A letter E appears in boldface type over the arrow.
D)A Greek letter #044; gamma>#044; is drawn over the arrow.
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