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Heat — Quiz Answers

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The temperature of a gas is increased. Which statement best explains the effect that this has on the motion of gas particles?

A
The average kinetic energy decreases, and the particles stop colliding.
B
The average kinetic energy increases, and the particles stop colliding.
C
The average kinetic energy increases, and the particles collide more frequently.
D
The average kinetic energy decreases, and the particles collide less frequently.
2
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What is thermal energy?

A
the total number of molecules in a system
B
the kinetic energy of particles in a system
C
the average overall volume of a system
D
the measure of temperature in a system
3

A student touches a freshly baked cake that was taken out of the oven. Which best explains why the cake feels hot?

A
Molecules in the skin are moving faster than molecules in the cake.
B
Molecules in the cake are moving faster than molecules in the skin.
C
The kinetic energy of molecules in the baking tray is more than the energy in the cake.
D
The kinetic energy of molecules in the cake is more than the energy in the baking tray.
4

In what type of reaction or process does heat flow into the system?

A
combustion
B
condensation
C
exothermic
D
endothermic
5

Which answer defines exothermic reaction ?

A
a process in which energy is absorbed as heat
B
a process in which energy is released as heat
C
a process in which energy is not present in a system
D
a process in which energy is stored and released
6

Which event is endothermic?

A
the change of water vapor to a liquid
B
the burning of a match
C
the combustion of propane gas
D
the melting of ice
7

A hot metal plate at 150 times degree C has been placed in air at room temperature. Which event would most likely take place over the next few minutes?

A
Molecules in both the metal and the surrounding air will start moving at lower speeds.
B
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
C
The air molecules that are surrounding the metal will slow down, and the molecules in the metal will speed up.
D
Molecules in both the metal and the surrounding air will start moving at higher speeds.
8

Which reaction is exothermic?

A
cap n sub 2 plus cap o sub 2 plus 181 kJ rightarrow 2 NO
B
cap n sub 4 NO sub 3 plus cap h sub 2 cap o plus 25 kJ rightarrow NH sub 4 raised to the plus aq power plus NO sub 3 raised to the negative aq power
C
2 cap h sub 2 cap o plus 286 kJ rightarrow 2 cap h sub 2 plus cap o sub 2
D
CH sub 4 plus 2 cap o sub 2 rightarrow CO sub 2 plus 2 cap h sub 2 cap o plus 891 kJ
9

Which statement about exothermic reactions is accurate?

A
Thermal energy is transferred from the product to the reacting substances.
B
As reactants form products, the potential energy decreases.
C
As reactants form products, the potential energy increases.
D
Thermal energy is transferred from the surroundings to the reacting substances.
10

Heat that flows by conduction is the transfer of thermal energy between substances in contact. What must occur for this to happen?

A
The two systems must not be touching each another.
B
One system must have higher kinetic energy than the other system.
C
The two systems must be the same temperature.
D
The thermal energy of one system must be the same as the thermal energy of the other system.

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Heat — Quiz Answers — Chemistry