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Unit 7 Exam

Total questions: 40

Worksheet time: 40mins

Name
Class
Date
1.

Which of these represents the release of chemical energy?

a)

warming food in a microwave

b)

pouring gasoline into a tank

c)

a toy running down a ramp

d)

burning charcoal in a grill

2.

A chemical equation is balanced by changing or adding

a)

chemical symbols

b)

reactants

c)

subscripts

d)

coefficients

3.

The substance that is formed in a chemical reaction is called the

a)

reactant

b)

radical

c)

polymer

d)

product

4.

Catalysts that slow reactions are called

a)

endothermic

b)

balanced

c)

inhibitors

d)

substrates

5.

Which of the following occurs in an endothermic reaction but not in an exothermic reaction?

a)

energy is absorbed

b)

atoms are rearranged

c)

molecules are formed

d)

chemical bonds are broken

6.

In a balanced chemical equation, the mass of the reactants is equal to the

a)

atoms in a molecule

b)

volume if the reactants

c)

atomic mass of the elements

d)

mass of the products

7.

Which of these is not a sign of a chemical reaction?

a)

the material dissolves

b)

heat is released

c)

a color change occurs

d)

a gas is given off

8.

when a chemical reaction and its reverse occur at the same time and rate, the reaction is said to be in

a)

redox

b)

imbalance

c)

equilibrium

d)

equality

9.

If you start with 5 mol of O2 in the reaction 2Mg + O2 -> 2MgO, how many moles of Mg will you need?

a)

10 mol

b)

8 mol

c)

4 mol

d)

5 mol

10.

Which of the following occurs when gasoline is burned?

a)

new elements are formed

b)

new molecules are formed

c)

new atoms are formed

d)

all the above

11.

Which of the following represents the word equation magnesium + oxygen -> magnesium oxide

a)

2Mg +O2 -> 2MgO

b)

MgO + O -> MgO2

c)

CH4 + O2 -> CH4O2

d)

2CH4 + O2 -> 2CH3OH

12.

In a redox reaction, the substance that accepts electrons is said to be

a)

reduced

b)

clarified

c)

oxidized

d)

electrified

13.

According to Le Chatelier's principle, opening a soda can produce bubbles because which of the following changes occurs in the bottle?

a)

Temperature increases

b)

Pressure increases

c)

Pressure decreases

d)

Temperature decreases

14.

All of the following factors may speed up a chemical reaction except

a)

presence of a catalyst

b)

higher pressure

c)

higher temperature

d)

smaller surface area

15.

A release of energy is a sign that

a)

oxygen is present

b)

a physical change has just occurred

c)

organic chemicals are present

d)

a chemical change is taking place

16.

A substance that undergoes a change in a chemical reaction is

a)

a chemical

b)

a reactant

c)

a product

d)

an enzyme

17.

Fragments of molecules that have at least one electron available for bonding are called

a)

protons

b)

ions

c)

radicals

d)

orbits

18.

What happens in a chemical reaction?

a)

atoms are destroyed

b)

atoms are rearranged

c)

atoms are created

d)

atoms are heated and cooled

19.

In an exothermic reaction, energy is transferred from

a)

one reactant to another

b)

the surroundings to the reactant

c)

the container to the chemicals

d)

the reactants to the surroundings

20.

A reaction in which the products contain more chemical energy that the reactants is

a)

endothermic

b)

electrical

c)

exothermic

d)

exergonic

21.

Chemical energy is energy that is

a)

released only when oxygen is present

b)

stored in the form of chemical bonds

c)

caused by the movement of electricity

d)

added to a reaction in the form of heat

22.

Which of the following equations is not balanced?

a)

Fe + S -> FeS

b)

KOH + HCl -> KCl +H2O

c)

2Mg + O2 -> 2MgO

d)

NaCl + H2SO4 -> Na2SO4 + HCl

23.

The energy source in photosynthesis is

a)

kinetic energy

b)

chemical energy

c)

heat energy

d)

light energy

24.

What coefficient is missing in C2H4 + (?)O2 -> 2CO2 + 2H2O?

a)

5

b)

4

c)

2

d)

3

25.

The product of the synthesis reaction between sodium and chlorine gas is

a)

sodium chloride

b)

copper(II) chloride

c)

carbon dioxide

d)

polyethylene

26.

A type of reaction that produces an increase in temperature is

a)

nonpolar

b)

endothermic

c)

exothermic

d)

covalent

27.

A slow reaction is likely to occur when the reactants have ____ temperatures and _____ surface areas.

a)

low, large

b)

low, small

c)

high, large

d)

high, small

28.

In an oxidation-reduction reaction,

a)

one substance gains electrons, the other loses electrons

b)

both substances lose electrons

c)

both substances gain electrons

d)

substances that give up electrons are reduced

29.

Which of the following represents a double-displacement reaction between sodium chloride and silver fluoride?

a)

NaCl + AgF -> NaF + Cl2 + Ag

b)

NaCl + AgF -> NaAgF + Cl2

c)

NaCl + AgF -> Ag + NaClF

d)

NaCl + AgF -> NaF + AgCl

30.

Which of the following is an example of a decomposition reaction?

a)

exchange of ions between two compounds

b)

digestion

c)

photosynthesis

d)

respiration

31.

Which of the following stores chemical energy?

a)

the temperature of a substance

b)

the density of a substance

c)

the nucleus of an atom

d)

the bonds of a molecule

32.

In the reaction 2H2O -> 2H2 + O2 if you start with 4 mol of water, how many moles of hydrogen gas are formed?

a)

6 mol

b)

2 mol

c)

8 mol

d)

4 mol

33.

Le Chatelier's principle states that increasing temperature favors a reaction that

a)

releases energy as heat

b)

involves an enzyme

c)

involves a chemical catalyst

d)

absorbs energy as heat

34.

An example of an endothermic reaction is

a)

photosynthesis by a plant

b)

burning gasoline

c)

an exploding firecracker

d)

bioluminescence by a firefly

35.

Give the mole ratio for the following equation: Zn + 2HCl -> ZnCl2 + H2

a)

1:2:1

b)

1:2:1:1

c)

1:1:1

d)

1:2:2:2

36.

2NaCl + H2SO4 -> Na2SO4 + 2HCl

a)

synthesis reaction

b)

decomposition reaction

c)

combustion reaction

d)

single-displacement reaction

e)

double-displacement reaction

37.

CH4 + 2O2 -> CO2 +2H2O

a)

synthesis reaction

b)

decomposition reaction

c)

combustion reaction

d)

single-displacement reaction

e)

double-displacement reaction

38.

2Li + 2H2O -> 2LiOH + H2

a)

synthesis reaction

b)

decomposition reaction

c)

combustion reaction

d)

single-displacement reaction

e)

double-displacement reaction

39.

Fe + S -> FeS

a)

synthesis reaction

b)

decomposition reaction

c)

combustion reaction

d)

single-displacement reaction

e)

double-displacement reaction

40.

2NH3 -> N2 + 3H2

a)

synthesis reaction

b)

decomposition reaction

c)

combustion reaction

d)

single-displacement reaction

e)

double-displacement reaction

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