AnswersKCPS Physics First 2027Heat

Heat — Quiz Answers

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1
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A student touches a freshly baked cake that was taken out of the oven. Which best explains why the cake feels hot?

A
The kinetic energy of molecules in the cake is more than the energy in the baking tray.
B
Molecules in the skin are moving faster than molecules in the cake.
C
Molecules in the cake are moving faster than molecules in the skin.
D
The kinetic energy of molecules in the baking tray is more than the energy in the cake.
2
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Which answer defines exothermic reaction ?

A
a process in which energy is not present in a system
B
a process in which energy is stored and released
C
a process in which energy is released as heat
D
a process in which energy is absorbed as heat
3

Which reaction is exothermic?

A
cap n sub 2 plus cap o sub 2 plus 181 kJ rightarrow 2 NO
B
CH sub 4 plus 2 cap o sub 2 rightarrow CO sub 2 plus 2 cap h sub 2 cap o plus 891 kJ
C
2 cap h sub 2 cap o plus 286 kJ rightarrow 2 cap h sub 2 plus cap o sub 2
D
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
4

What is thermal energy?

A
the measure of temperature in a system
B
the total number of molecules in a system
C
the average overall volume of a system
D
the kinetic energy of particles in a system
5

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

A
One system must have higher kinetic energy than the other system.
B
The thermal energy of one system must be the same as the thermal energy of the other system.
C
The two systems must be the same temperature.
D
The two systems must not be touching each another.
6

Which statement about exothermic reactions is accurate?

A
Thermal energy is transferred from the surroundings to the reacting substances.
B
As reactants form products, the potential energy decreases.
C
Thermal energy is transferred from the product to the reacting substances.
D
As reactants form products, the potential energy increases.
7

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

A
exothermic
B
endothermic
C
combustion
D
condensation
8

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 increases, and the particles collide more frequently.
B
The average kinetic energy decreases, and the particles stop colliding.
C
The average kinetic energy decreases, and the particles collide less frequently.
D
The average kinetic energy increases, and the particles stop colliding.
9

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
The air molecules that are surrounding the metal will speed up, and the molecules in the metal will slow down.
B
Molecules in both the metal and the surrounding air will start moving at lower speeds.
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.
10

Which event is endothermic?

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

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Heat — Quiz Answers — KCPS Physics First 2027