Kinetic Theory and First Law of Thermodynamics MCQs

Question 1

Joule's paddle-wheel experiment showed that:

Accepted Answer

mechanical work can raise internal energy just as heating can

Answer

temperature is energy

Answer

work cannot be converted to heat

Answer

heat is a fluid

Question 2

The number of moles in 3.01 10^23 molecules is:

Accepted Answer

0.5 mol

Answer

1.81 10^47 mol

Answer

3.01 mol

Answer

2 mol

Question 3

A gas in a rigid container is heated. All the heat supplied goes into:

Accepted Answer

increasing internal energy (raising its temperature)

Answer

moving the container

Answer

work done by the gas

Answer

nothing

Question 4

A gas at 1 10^5 Pa, 2 L and 300 K is changed to 2 10^5 Pa and 600 K. Its new volume is:

Accepted Answer

2 L

Answer

1 L

Answer

8 L

Answer

4 L

Question 5

A graph of p against V for a gas at constant temperature is:

Accepted Answer

a curve (hyperbola), p falling as V rises

Answer

a straight line through the origin

Answer

a vertical line

Answer

a horizontal line

Question 6

A fixed mass of gas at 100 kPa occupies 30 L. At constant temperature it is changed to 20 L. The new pressure is:

Accepted Answer

150 kPa

Answer

75 kPa

Answer

300 kPa

Answer

66.7 kPa

Question 7

The first law does NOT tell us:

Accepted Answer

the direction in which heat flows naturally

Answer

that energy is conserved

Answer

how heat and work change internal energy

Answer

that Delta U = Q - W

Question 8

When work is done on a gas (with no heat flow), its internal energy:

Accepted Answer

increases

Answer

decreases

Answer

becomes zero

Answer

stays the same

Question 9

The product kT at 300 K is about:

Accepted Answer

4.1 10^-21 J

Answer

2.5 10^3 J

Answer

4.1 10^-25 J

Answer

1.8 10^26 J

Question 10

A gas absorbs 300 J of heat and does 300 J of work. The change in its internal energy is: (Use Q = Delta U + W, where Q = heat supplied to the gas and W = work done by the gas.)

Accepted Answer

0 J

Answer

600 J

Answer

100 J

Answer

50 J

Question 11

1 10^23 molecules of an ideal gas at 300 K fill 0.001 m^3. The pressure is (k = 1.38 10^-23 J/K):

Accepted Answer

4.14 10^5 Pa

Answer

41,400 Pa

Answer

4.14 10^6 Pa

Answer

8.28 10^5 Pa

Question 12

An isolated system has Q = 0 and W = 0, so its internal energy:

Accepted Answer

remains constant

Answer

becomes zero

Answer

decreases

Answer

increases

Question 13

At constant temperature, compressing a gas raises its pressure because:

Accepted Answer

the same molecules hit a smaller wall area more often

Answer

they lose energy

Answer

they move faster

Answer

they become heavier

Question 14

Car tyre pressure is higher after a long drive because:

Accepted Answer

the air in the tyres gets warmer at roughly constant volume

Answer

air leaks in

Answer

the air molecules multiply

Answer

the tyre shrinks

Question 15

Two bodies in thermal equilibrium must have the same:

Accepted Answer

temperature

Answer

volume

Answer

heat content

Answer

specific heat capacity

Question 16

A perpetual motion machine of the first kind is impossible because:

Accepted Answer

energy cannot be created

Answer

heat flows from cold to hot

Answer

friction is zero

Answer

entropy always decreases

Question 17

A thermometer gives a correct reading only when:

Accepted Answer

it has reached thermal equilibrium with the body

Answer

it is colder than the body

Answer

it is hotter than the body

Answer

it is first heated

Question 18

A metal spoon and a wooden spoon in the same room feel different to touch, yet they are:

Accepted Answer

at the same temperature

Answer

both at 0 °C

Answer

at different temperatures

Answer

both at body temperature

Question 19

An aerosol can feels cold after spraying for a while because:

Accepted Answer

the expanding gas does work and loses internal energy

Answer

heat flows in

Answer

work is done on the gas

Answer

the liquid is refrigerated

Question 20

The average translational kinetic energy of a gas molecule at 273 K is (k = 1.38 10^-23 J/K):

Accepted Answer

5.65 10^-21 J

Answer

1.7 10^-20 J

Answer

3.77 10^-21 J

Answer

1.13 10^-20 J

Question 21

Gas molecules are assumed to move:

Accepted Answer

randomly in all directions

Answer

all at the same speed in one direction

Answer

only along one axis

Answer

only upward

Question 22

pV = nRT and pV = NkT are the same equation because:

Accepted Answer

nR = Nk

Answer

nk = NR

Answer

n = N

Answer

R = k

Question 23

At low temperature a real gas departs from ideal behaviour because:

Accepted Answer

intermolecular attractions become significant

Answer

molecules disappear

Answer

molecules move faster

Answer

pressure becomes infinite

Question 24

In thermal equilibrium, molecules of two gases in contact have the same:

Accepted Answer

average translational kinetic energy

Answer

mass

Answer

speed

Answer

number

Question 25

If the absolute temperature of an ideal gas doubles, the average KE of its molecules:

Accepted Answer

doubles

Answer

stays the same

Answer

halves

Answer

quadruples

Kinetic Theory and First Law of Thermodynamics MCQs — Physics (page 4)

76. Joule's paddle-wheel experiment showed that:

77. The number of moles in 3.01 10^23 molecules is:

78. A gas in a rigid container is heated. All the heat supplied goes into:

79. A gas at 1 10^5 Pa, 2 L and 300 K is changed to 2 10^5 Pa and 600 K. Its new volume is:

80. A graph of p against V for a gas at constant temperature is:

81. A fixed mass of gas at 100 kPa occupies 30 L. At constant temperature it is changed to 20 L. The new pressure is:

82. The first law does NOT tell us:

83. When work is done on a gas (with no heat flow), its internal energy:

84. The product kT at 300 K is about:

85. A gas absorbs 300 J of heat and does 300 J of work. The change in its internal energy is: (Use Q = Delta U + W, where Q = heat supplied to the gas and W = work done by the gas.)

86. 1 10^23 molecules of an ideal gas at 300 K fill 0.001 m^3. The pressure is (k = 1.38 10^-23 J/K):

87. An isolated system has Q = 0 and W = 0, so its internal energy:

88. At constant temperature, compressing a gas raises its pressure because:

89. Car tyre pressure is higher after a long drive because:

90. Two bodies in thermal equilibrium must have the same:

91. A perpetual motion machine of the first kind is impossible because:

92. A thermometer gives a correct reading only when:

93. A metal spoon and a wooden spoon in the same room feel different to touch, yet they are:

94. An aerosol can feels cold after spraying for a while because:

95. The average translational kinetic energy of a gas molecule at 273 K is (k = 1.38 10^-23 J/K):

96. Gas molecules are assumed to move:

97. pV = nRT and pV = NkT are the same equation because:

98. At low temperature a real gas departs from ideal behaviour because:

99. In thermal equilibrium, molecules of two gases in contact have the same:

100. If the absolute temperature of an ideal gas doubles, the average KE of its molecules:

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