AnswersMO-Physical Science A-CRUnit Test

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1
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Two substances did not react with each other as expected. What is the most likely reason?

A
It was heated.
B
It was hit with a hammer.
C
It was placed in a salt solution.
D
It was frozen.
2
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If a catalyst lowers the activation energy, what raises the activation energy?

A
heat
B
a reaction
C
another catalyst
D
an inhibitor
3

Why is reaching activation energy necessary?

A
Reactants require a minimum amount of energy to start to break a chemical bond.
B
Products require a minimum amount of energy to start to break a chemical bond.
C
Reactants must have the maximum amount of energy to start to break a chemical bond.
D
Products must have the maximum amount of energy to start to break a chemical bond.
4

Four canisters contain helium gas.

Question illustration
A
W
B
X
C
Y
D
Z
5

The pictures represent three different states of matter.

Question illustration
A
X → Y → Z
B
Z → Y → X
C
Y → Z → X
D
Y → X → Z
6

Food can spoil very quickly. Which methods are used to minimize the reactions that allow bacteria and fungi to grow?

A
preservatives and low temperature
B
high temperature and preservatives
C
catalysts and high temperatures
D
low temperatures and catalysts
7

There are a few ways to increase the rate of a reaction. What is altered when the amount of a substance in a given volume is increased?

A
temperature
B
concentration
C
surface area
D
pressure
8

Which describes a scenario that would most likely use an inhibitor?

A
During activity, sugar is converted to energy.
B
When at rest, the body stores sugar.
C
After a meal, protein digestion occurs in the stomach.
D
Before a meal, digestive juices are preparing for food.
9

The typical speed of a reaction releases gas every twenty seconds for two minutes. The chart lists four substances that were added to the reaction at different times. Which statement best summarizes the chart?

Question illustration
A
Substances W and Y are catalysts, and substances X and Z are inhibitors.
B
Substance W is an inhibitor, and substances X, Y, and Z are catalysts.
C
Substances W and Z are inhibitors, and substances X and Y are catalysts.
D
Substance X is a catalyst, and substances W, Y, and Z are inhibitors.
10

Enzymes are added to a chemical reaction to lower the activation energy. What is an enzyme classified as?

A
a catalyst
B
an inhibitor
C
an accelerator
D
a depressant
11

Three students are working with different substances to measure the chemical changes that occur. Chao is working with milk, Mia is working with carbon dioxide gas, and Ezra is working with rock. Which would best describe the way to treat each substance to get a faster reaction?

A
Chao should change the temperature, Mia should adjust the pressure, and Ezra should increase the surface area.
B
Chao should change the concentration, Mia should adjust the temperature, and Ezra should increase the surface area.
C
Chao should change the temperature, Mia should adjust the concentration, and Ezra should decrease the surface area.
D
Chao should change the concentration, Mia should adjust the pressure, and Ezra should decrease the surface area.
12

The numbers represent the change in energy for a chemical reaction.Which number would result from an endothermic reaction?

Question illustration
A
–212
B
0
C
-1
D
800
13

The chart shows the path reactants take to become products.

Question illustration
A
Heat was removed from the activation energy to create the product.
B
Heat was added to create the product.
C
The products have less energy than the reactants.
D
The products have the same energy as the reactants.
14

To break a chemical bond, particles need to collide with a certain amount of

A
energy.
B
atoms.
C
molecules.
D
chemicals.

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