Question 1

A slow (quasi-static) process is NOT reversible if:

Accepted Answer

A)  the temperature changes 
B)  energy is absorbed or emitted as heat 
C)  work is done on the system 
D)  friction is present 
E)  the pressure changes 
A)  the temperature changes 
B)  energy is absorbed or emitted as heat 
C)  work is done on the system 
D)  friction is present 
E)  the pressure changes

Question 2

Which of the following is NOT a state variable?

Accepted Answer

A)  Work 
B)  Internal energy 
C)  Entropy 
D)  Temperature 
E)  Pressure 
A)  Work 
B)  Internal energy 
C)  Entropy 
D)  Temperature 
E)  Pressure

Question 3

Let k be the Boltzmann constant. If the configuration of molecules in a gas changes from one with a multiplicity of M1 to one with a multiplicity of M2, then entropy changes by:

Accepted Answer

A) $\Delta$S = 0 
B)  $\Delta$S = k(M2 - M1) 
C)  $\Delta$S = kM2/M1 
D)  $\Delta$S = k ln(M2M1) 
E)  $\Delta$S = k ln(M2/M1) 
A) $\Delta$S = 0 
B)  $\Delta$S = k(M2 - M1) 
C)  $\Delta$S = kM2/M1 
D)  $\Delta$S = k ln(M2M1) 
E)  $\Delta$S = k ln(M2/M1)

Question 4

On a warm day a pool of water transfers energy to the air as heat and freezes. This is a direct violation of:

Accepted Answer

A)  the zeroth law of thermodynamics 
B)  the first law of thermodynamics 
C)  the second law of thermodynamics 
D)  the third law of thermodynamics 
E)  none of the above 
A)  the zeroth law of thermodynamics 
B)  the first law of thermodynamics 
C)  the second law of thermodynamics 
D)  the third law of thermodynamics 
E)  none of the above

Question 5

The thermodynamic state of gas changes configuration from one with 3.8 * 1018 microstates to one with 7.9 *1019 microstates. The Boltzmann constant is 1.38 *10-23 J/K. The change in entropy is:

Accepted Answer

A)  $\Delta$S = 0 
B)  $\Delta$S = 1.05 * 10-23 J/K 
C)  $\Delta$S = -1.05 *10-23 J/K 
D)  $\Delta$S = 4.19*10-23 J/K 
E)  $\Delta$S = -4.19 *10-23 J/K 
A)  $\Delta$S = 0 
B)  $\Delta$S = 1.05 * 10-23 J/K 
C)  $\Delta$S = -1.05 *10-23 J/K 
D)  $\Delta$S = 4.19*10-23 J/K 
E)  $\Delta$S = -4.19 *10-23 J/K

Question 6

A heat engine operates between 200 K and 100 K. In each cycle it takes 100 J from the hot reservoir, loses 25 J to the cold reservoir, and does 75 J of work. This heat engine violates:

Accepted Answer

A)  both the first and second laws of thermodynamics 
B)  the first law but not the second law of thermodynamics 
C)  the second law but not the first law of thermodynamics 
D)  neither the first law nor the second law of thermodynamics 
E)  cannot answer without knowing the mechanical equivalent of heat 
A)  both the first and second laws of thermodynamics 
B)  the first law but not the second law of thermodynamics 
C)  the second law but not the first law of thermodynamics 
D)  neither the first law nor the second law of thermodynamics 
E)  cannot answer without knowing the mechanical equivalent of heat

Question 7

For a system of molecules,

Accepted Answer

A)  each configuration consists of a set of equivalent microstates. 
B)  each microstate consists of a set of equivalent configurations. 
C)  the number of configurations in a microstate is the multiplicity of the microstate. 
D)  the multiplicity of the configuration is the product of the number of molecules in each microstate. 
E)  each configuration is equally probable. 
A)  each configuration consists of a set of equivalent microstates. 
B)  each microstate consists of a set of equivalent configurations. 
C)  the number of configurations in a microstate is the multiplicity of the microstate. 
D)  the multiplicity of the configuration is the product of the number of molecules in each microstate. 
E)  each configuration is equally probable.

Question 8

A heat engine in each cycle absorbs energy from a reservoir as heat and does an equivalent amount of work, with no other changes. This engine violates:

Accepted Answer

A)  the zeroth law of thermodynamics 
B)  the first law of thermodynamics 
C)  the second law of thermodynamics 
D)  the third law of thermodynamics 
E)  none of the above 
A)  the zeroth law of thermodynamics 
B)  the first law of thermodynamics 
C)  the second law of thermodynamics 
D)  the third law of thermodynamics 
E)  none of the above

Question 9

A heat engine:

Accepted Answer

A)  converts heat input to an equivalent amount of work 
B)  converts work to an equivalent amount of heat 
C)  takes heat in, does work, and loses energy as heat 
D)  uses positive work done on the system to transfer heat from a low temperature reservoir to a high temperature reservoir 
E)  uses positive work done on the system to transfer heat from a high temperature reservoir to a low temperature reservoir 
A)  converts heat input to an equivalent amount of work 
B)  converts work to an equivalent amount of heat 
C)  takes heat in, does work, and loses energy as heat 
D)  uses positive work done on the system to transfer heat from a low temperature reservoir to a high temperature reservoir 
E)  uses positive work done on the system to transfer heat from a high temperature reservoir to a low temperature reservoir

Question 10

In a thermally insulated kitchen, an ordinary refrigerator is turned on and its door is left open. The temperature of the room:

Accepted Answer

A)  remains constant according to the first law of thermodynamics 
B)  increases according to the first law of thermodynamics 
C)  decreases according to the first law of thermodynamics 
D)  remains constant according to the second law of thermodynamics 
E)  increases according to the second law of thermodynamics 
A)  remains constant according to the first law of thermodynamics 
B)  increases according to the first law of thermodynamics 
C)  decreases according to the first law of thermodynamics 
D)  remains constant according to the second law of thermodynamics 
E)  increases according to the second law of thermodynamics

Question 11

Rank from smallest to largest, the changes in entropy of a pan of water on a hot plate, as the temperature of the water

Accepted Answer

A)  1, 2, 3, 4 
B)  3, 4, 1, 2 
C)  1 and 2 tie, then 3 and 4 tie 
D)  3 and 4 tie, then 1 and 2 tie 
E)  4, 3, 2, 1 
A)  1, 2, 3, 4 
B)  3, 4, 1, 2 
C)  1 and 2 tie, then 3 and 4 tie 
D)  3 and 4 tie, then 1 and 2 tie 
E)  4, 3, 2, 1

Question 12

A Carnot engine operates between 200 $\degree$C and 20 $\degree$C. Its maximum possible efficiency is:

Accepted Answer

A)  90% 
B)  100% 
C)  38% 
D)  72% 
E)  24% 
A)  90% 
B)  100% 
C)  38% 
D)  72% 
E)  24%

Question 13

A perfectly reversible heat pump with a coefficient of performance of 14 supplies energy to a building as heat to maintain its temperature at 27 $\degree$C. If the pump motor does work at the rate of 1 kW, at what rate does the pump supply energy to the building?

Accepted Answer

A)  15 kW 
B)  3.9 kW 
C)  1.4 kW 
D)  0.26 kW 
E)  0.067 kW 
A)  15 kW 
B)  3.9 kW 
C)  1.4 kW 
D)  0.26 kW 
E)  0.067 kW

Question 14

For a system of molecules,

Accepted Answer

A)  each configuration is equally probable. 
B)  microstates with more configurations are more probable than other microstates. 
C)  configurations with more microstates are more probable than other configurations. 
D)  microstates with more configurations are less probable than other microstates. 
E)  configurations with more microstates are less probable than other configurations. 
A)  each configuration is equally probable. 
B)  microstates with more configurations are more probable than other microstates. 
C)  configurations with more microstates are more probable than other configurations. 
D)  microstates with more configurations are less probable than other microstates. 
E)  configurations with more microstates are less probable than other configurations.

Question 15

The difference in entropy $\Delta$S = SB - SA for two states A and B of a system can computed as the integral $\int$ dQ/T provided:

Accepted Answer

A)  A and B are on the same adiabat 
B)  A and B have the same temperature 
C)  a reversible path is used for the integral 
D)  the change in internal energy is first computed 
E)  the energy absorbed as heat by the system is first computed 
A)  A and B are on the same adiabat 
B)  A and B have the same temperature 
C)  a reversible path is used for the integral 
D)  the change in internal energy is first computed 
E)  the energy absorbed as heat by the system is first computed

Question 16

According to the second law of thermodynamics:

Accepted Answer

A)  all heat engines have the same efficiency 
B)  all reversible heat engines have the same efficiency 
C)  the efficiency of any heat engine is independent of its working substance 
D)  the efficiency of a Carnot engine depends only on the temperatures of the two reservoirs 
E)  all Carnot engines theoretically have 100% efficiency 
A)  all heat engines have the same efficiency 
B)  all reversible heat engines have the same efficiency 
C)  the efficiency of any heat engine is independent of its working substance 
D)  the efficiency of a Carnot engine depends only on the temperatures of the two reservoirs 
E)  all Carnot engines theoretically have 100% efficiency

Question 17

For all irreversible processes involving a system and its environment:

Accepted Answer

A)  the entropy of the system does not change 
B)  the entropy of the system increases 
C)  the total entropy of the system and its environment does not change 
D)  the total entropy of the system and its environment increases 
E)  none of the above 
A)  the entropy of the system does not change 
B)  the entropy of the system increases 
C)  the total entropy of the system and its environment does not change 
D)  the total entropy of the system and its environment increases 
E)  none of the above

Question 18

Consider the following processes:   Which are never found to occur?

Accepted Answer

A)  Only I 
B)  Only II 
C)  Only III 
D)  Only II and III 
E)  I, II and III 
A)  Only I 
B)  Only II 
C)  Only III 
D)  Only II and III 
E)  I, II and III

Question 19

An inventor claims to have a heat engine that has efficiency of 40% when it operates between a high temperature reservoir of 150 $\degree$C and a low temperature reservoir of 30 $\degree$C. This engine:

Accepted Answer

A)  must violate the zeroth law of thermodynamics 
B)  must violate the first law of thermodynamics 
C)  must violate the second law of thermodynamics 
D)  must violate the third law of thermodynamics 
E)  does not necessarily violate any of the laws of thermodynamics 
A)  must violate the zeroth law of thermodynamics 
B)  must violate the first law of thermodynamics 
C)  must violate the second law of thermodynamics 
D)  must violate the third law of thermodynamics 
E)  does not necessarily violate any of the laws of thermodynamics

Question 20

A reversible refrigerator operates between a low temperature reservoir at TL and a high temperature reservoir at TH. Its coefficient of performance is given by:

Accepted Answer

A)  (TH - TL)/ TL 
B)  TL /(TH - TL) 
C)  (TH - TL)/TH 
D)  TH/(TH - TL) 
E)  TH(TH + TL) 
A)  (TH - TL)/ TL 
B)  TL /(TH - TL) 
C)  (TH - TL)/TH 
D)  TH/(TH - TL) 
E)  TH(TH + TL)

Exam 20: Entropy and the Second Law of Thermodynamics

A slow (quasi-static) process is NOT reversible if:

Which of the following is NOT a state variable?

Let k be the Boltzmann constant. If the configuration of molecules in a gas changes from one with a multiplicity of M1 to one with a multiplicity of M2, then entropy changes by:

On a warm day a pool of water transfers energy to the air as heat and freezes. This is a direct violation of:

The thermodynamic state of gas changes configuration from one with 3.8 * 1018 microstates to one with 7.9 *1019 microstates. The Boltzmann constant is 1.38 *10-23 J/K. The change in entropy is:

A heat engine operates between 200 K and 100 K. In each cycle it takes 100 J from the hot reservoir, loses 25 J to the cold reservoir, and does 75 J of work. This heat engine violates:

For a system of molecules,

A heat engine in each cycle absorbs energy from a reservoir as heat and does an equivalent amount of work, with no other changes. This engine violates:

A heat engine:

In a thermally insulated kitchen, an ordinary refrigerator is turned on and its door is left open. The temperature of the room:

Rank from smallest to largest, the changes in entropy of a pan of water on a hot plate, as the temperature of the water

A Carnot engine operates between 200 °\degree° C and 20 °\degree° C. Its maximum possible efficiency is:

A perfectly reversible heat pump with a coefficient of performance of 14 supplies energy to a building as heat to maintain its temperature at 27 °\degree° C. If the pump motor does work at the rate of 1 kW, at what rate does the pump supply energy to the building?

For a system of molecules,

The difference in entropy Δ\DeltaΔ S = SB - SA for two states A and B of a system can computed as the integral ∫\int∫ dQ/T provided:

According to the second law of thermodynamics:

For all irreversible processes involving a system and its environment:

Consider the following processes: Which are never found to occur?

An inventor claims to have a heat engine that has efficiency of 40% when it operates between a high temperature reservoir of 150 °\degree° C and a low temperature reservoir of 30 °\degree° C. This engine:

A reversible refrigerator operates between a low temperature reservoir at TL and a high temperature reservoir at TH. Its coefficient of performance is given by:

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Let k be the Boltzmann constant. If the configuration of molecules in a gas changes from one with a multiplicity of M₁ to one with a multiplicity of M₂, then entropy changes by:

The thermodynamic state of gas changes configuration from one with 3.8 * 10¹⁸ microstates to one with 7.9 10¹⁹ microstates. The Boltzmann constant is 1.38 10^-23 J/K. The change in entropy is:

A Carnot engine operates between 200 $\degree$ C and 20 $\degree$ C. Its maximum possible efficiency is:

A perfectly reversible heat pump with a coefficient of performance of 14 supplies energy to a building as heat to maintain its temperature at 27 $\degree$ C. If the pump motor does work at the rate of 1 kW, at what rate does the pump supply energy to the building?

The difference in entropy $\Delta$ S = S_B - S_A for two states A and B of a system can computed as the integral $\int$ dQ/T provided:

An inventor claims to have a heat engine that has efficiency of 40% when it operates between a high temperature reservoir of 150 $\degree$ C and a low temperature reservoir of 30 $\degree$ C. This engine:

A reversible refrigerator operates between a low temperature reservoir at T_L and a high temperature reservoir at T_H. Its coefficient of performance is given by: