Multiple Choice
Identify the
letter of the choice that best completes the statement or answers the question.
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1.
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Every
chemical reaction involves a change in a. | mass. | b. | energy. | c. | concentration. | d. | state. | | |
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2.
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In a
chemical reaction, a. | there is no change in energy. | b. | energy is always
absorbed. | c. | energy is always released. | d. | energy is either
absorbed or released. | | |
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3.
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The
force that holds atoms together is called a. | a chemical bond. | b. | conservation of
matter. | c. | heat. | d. | a chemical
change. | | |
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4.
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A
shorter, easier way to show chemical reactions, using symbols instead of words, is
called a a. | chemical
equation. | b. | chemical formula. | c. | symbol. | d. | subscript. | | |
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5.
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The
substances listed on the left side of a chemical equation are the a. | products. | b. | coefficients. | c. | precipitates. | d. | reactants. | | |
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6.
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In an
equation, numbers often appear in front of a chemical formula. These numbers tell you the number of
a. | atoms in each
molecule in the reaction. | b. | elements in the reaction. | c. | molecules or
atoms of each substance in the reaction. | d. | molecules in each atom in the
reaction. | | |
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7.
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How
many atoms in total does a molecule of C3H8 have?
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8.
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Which
of the following shows a correct structure for a chemical equation? a. | Product +
Product ®
Reactant | b. | Product + Reactant ® Product + Reactant | c. | Product +
Product ¬ Reactant +
Reactant | d. | Reactant + Reactant ® Product | | |
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9.
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In
chemical reactions, what does the principle of conservation of mass mean? a. | Matter is not
created or destroyed. | b. | The total mass of the reactants is greater than the total mass
of the products. | c. | The total mass of the reactants is less than the total mass of
the products. | d. | Matter is not changed. | | |
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10.
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Which
of the following is a balanced chemical equation? a. | H2O2 ® H2O
+ O2 | b. | 2 Fe2O3 + 3 C ® 4 Fe + 3
CO2 | c. | SO2 + O2 + 2 H2O ® 4
H2SO4 | d. | 2 Mg + HCl ® MgCl2 + H2 | | |
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11.
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To
balance the chemical equation in which hydrogen and oxygen are combined to yield water
(H2 + O2 ® H2O), you would change a. | only the
coefficient of H2 to 2. | b. | only the coefficient of O2 to
2. | c. | the coefficients
of both H2 and H2O to 2. | d. | the coefficients
of both O2 and H2O to 2. | | |
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12.
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According to the principle of conservation of mass, in a chemical equation the number
of a. | coefficients for
the products equals the number of coefficients for the reactants. | b. | reactants equals
the number of products. | c. | atoms in the products equals the number of atoms in the
reactants. | d. | subscripts for the products equals the number of subscripts for
the reactants. | | |
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Modified True/False
Indicate
whether the sentence or statement is true or false. If false, change the identified word or
phrase to make the sentence or statement true.
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13.
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Chemical reactions that absorb energy are said to be exothermic.
_________________________
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14.
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The
materials present at the beginning of a chemical reaction are called the products.
_________________________
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15.
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The
number 2 in the formula CO2 is a subscript. _________________________
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16.
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The
amount of matter in a chemical reaction changes. _________________________
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Completion
Complete each sentence or
statement.
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17.
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A
precipitate is a(n) ____________________ that forms from solution during a chemical
reaction.
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18.
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A
reaction that ____________________ energy in the form of heat is an exothermic
reaction.
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19.
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A
reaction that absorbs energy is called a(n) _________________________ reaction.
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20.
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A
chemical _________________________ uses symbols to show a chemical reaction.
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21.
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The
_________________________ are the substances you have at the beginning of a chemical
reaction.
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22.
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The
substances that form as a result of a chemical reaction are the
_________________________.
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23.
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In a
chemical equation, you read the arrow as “_________________________.”
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24.
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A
molecule of table sugar, C12H22O11, has a total of
____________________ atoms.
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25.
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A
subscript shows the number of ____________________ of an element in a molecule.
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26.
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The
balanced chemical equation
P4O10 + 6 H2O ® 4 H3PO4 tells you that ____________________ molecules
of H3PO4 are formed in the reaction.
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27.
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The
principle of ______________________________ states that during a chemical reaction, matter is not
created or destroyed.
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28.
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A
number called the _________________________ is placed in front of a chemical formula in an
equation.
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29.
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Chemists say an equation is _________________________ when it shows the same number of
each type of atom on both sides of the equation.
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Short Answer
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30.
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Identify the reactant(s) and product(s) of the reaction.
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31.
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In
the formula for water (H2O), what does the number 2 tell you?
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32.
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Where
does the water come from in the reaction?
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33.
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Write
a balanced equation for the reaction.
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34.
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Is
the formation of a gas always an indication that a chemical reaction has taken place? Explain your
answer.
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35.
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Compare and contrast a chemical formula and a chemical equation.
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Essay
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36.
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Explain which bonds are broken and which bonds are formed during the reaction of
magnesium and oxygen to form magnesium oxide (2 Mg + O2 ® 2 MgO). Identify which substances are compounds and which are
elements.
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37.
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Relate the writing and balancing of a chemical equation to the principle of
conservation of mass.
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