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  • Stage 1

    Answer 3 questions correctly in a row.

When a chemical reaction absorbs or releases thermal energy, the reaction causes a change in temperature. Read the passage about a chemical reaction that absorbs or releases thermal energy. Then, follow the instructions below.
The gasoline used in cars today is a mixture of over 
1,000
 different substances. One of these substances is isooctane 
(
C
8
H
18
)
. In a car engine, isooctane reacts with oxygen 
(
O
2
)
 to produce carbon dioxide 
(
C
O
2
)
 and water 
(
H
2
O
)
. During the reaction, a large amount of thermal energy is released into the surroundings. This thermal energy is used to power the car.
Complete the statement.
During this chemical reaction, the 
car engine
 becomes 
warmer

.
ref_doc_title.

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