AnswersPhysical ScienceIntroduction to Chemical Reactions

Introduction to Chemical Reactions — Quiz Answers

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1
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Which statement best describes the difference between endothermic and exothermic reactions?

A
They are opposites because endothermic reactions release energy and exothermic reactions require energy.
B
They are opposites because endothermic reactions require energy and exothermic reactions release energy.
C
They the same because they are both ways of forming precipitates.
D
They the same because they are both ways of forming gasses.
2
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Two chemicals react in an endothermic reaction. What can be known about this reaction?

A
A precipitate will form as a result of the reaction.
B
A gas will form as a result of the reaction.
C
Heat is absorbed because the old substance needs more energy to break its bonds.
D
Heat is released because the old substance needs less energy to break its bonds.
3

Which is an example of a chemical reaction?

A
paper soaked in water
B
paper folded into tiny pieces
C
paper shredded and turned into pulp
D
paper burned and turned into smoke
4

Which best describes what is occurring in the reaction? When vinegar and baking soda react, the mixture becomes cold to the touch and a gas and a new liquid substance are formed.

A
The reaction is non-chemical and exothermic.
B
The reaction is chemical and exothermic.
C
The reaction is chemical and endothermic.
D
The reaction is non-chemical and endothermic.
6

Which is evidence that a chemical reaction has likely occurred?

A
boiling water releasing steam
B
a liquid slowly losing volume
C
a change in the shape of a solid
D
the formation of a precipitate
7

When baking soda and vinegar react, the surface bubbles. What does this most likely indicate?

A
a chemical change, because a gas is being formed
B
a non-chemical change, because a gas is being formed
C
a chemical change, because a precipitate is being formed
D
a non-chemical change, because a precipitate is being formed
8

Which best describes what happens to the atoms in a chemical reaction?

A
all of them form stronger bonds
B
they are rearranged
C
all of them remain unchanged
D
many of them disappear
9

What does this represent about the type of change happening in the container? Theresa creates an experiment where she mixes two red-colored substances together in a container and observes the solution slowly changing from red to blue for the next eight minutes. The solution becomes completely blue after eight minutes.

A
A non-chemical change occurred at four minutes.
B
A non-chemical change started immediately and finished at eight minutes.
C
A chemical change started immediately and finished at eight minutes.
D
A chemical change occurred at four minutes.
10

Which of these most likely represents a chemical change?

A
sugars digested by saliva
B
water boiling
C
ice cream melting
D
mud drying to dirt

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