Second law of thermodynamics, reversible and irreversible processes - One Line Questions
1.
Consider a heat engine operating between 500 K and 300 K. If the engine is reversible, its maximum possible efficiency is: —
0.6
2.
The efficiency of a reversible heat engine operating between temperatures T1 (hot) and T2 (cold) is given by: —
1 - T2/T1
3.
An irreversible process can be characterized by: —
A net increase in entropy of the universe.
4.
Which phenomenon demonstrates the irreversibility of natural processes? —
The mixing of two different gases at room temperature.
5.
Heat transfer due to a finite temperature difference is: —
An irreversible process
6.
The process of rusting of iron is an example of: —
An irreversible process
7.
In a reversible process, the work done by the system is: —
Always greater than the work done in an irreversible process between the same states.
8.
For any process occurring in an isolated system, the total entropy change is: —
Zero or positive
9.
The Carnot cycle is an example of a cycle that operates between two heat reservoirs. It is: —
A reversible cycle
10.
The second law of thermodynamics is often referred to as the law of: —
Increasing entropy
11.
The second law of thermodynamics is fundamentally about the: —
Direction of natural processes
12.
The second law of thermodynamics implies that it is impossible to: —
All of the above.
13.
The entropy of the universe tends to: —
Increase in all spontaneous processes.
14.
Which of the following is a consequence of the second law of thermodynamics? —
Both B and C.
15.
Which statement about entropy is correct? —
Entropy is a measure of the randomness or disorder in a system.
16.
The efficiency of any real heat engine (irreversible) operating between two temperatures is always: —
Less than the Carnot efficiency.
17.
If a process is irreversible, then the change in entropy of the system plus the change in entropy of the surroundings is: —
Greater than zero
18.
Which of the following processes is best approximated as a reversible process in many thermodynamic analyses? —
Slow evaporation of a liquid
19.
A refrigerator's operation is based on which principle? —
Second law of thermodynamics (Clausius statement)
20.
If a system undergoes a reversible isothermal expansion, then: —
Work is done by the system.
21.
A gas expands isothermally and reversibly. In this process: —
All of the above.
22.
The maximum efficiency of a heat engine is achieved when it operates on a: —
Carnot cycle
23.
A process that can be reversed by an infinitesimal change in conditions, restoring both the system and surroundings to their initial states, is called: —
Reversible process
24.
The entropy of a system can decrease if: —
It exchanges heat with the surroundings, and the entropy increase of the surroundings is greater than the entropy decrease of the system.
25.
The Clausius statement of the second law of thermodynamics states that: —
It is impossible to transfer heat from a colder body to a hotter body without the aid of an external agent.
26.
Which of the following is a necessary condition for a process to be reversible? —
The temperature difference between the system and surroundings must be zero.
27.
Which condition is essential for a process to be reversible? —
The process must occur infinitely slowly.
28.
Which of the following conditions must be met for a process to be considered reversible? —
It must be carried out infinitely slowly, with the system always in equilibrium with its surroundings.
29.
The statement 'heat cannot spontaneously flow from a colder body to a hotter body' is attributed to: —
Clausius
30.
Which of the following is NOT a characteristic of a reversible process? —
Involves dissipative forces like friction.
31.
For a system undergoing a reversible adiabatic process, the change in entropy is: —
Zero
32.
If a system absorbs heat Q reversibly at temperature T, the change in its entropy is: —
Q/T
33.
A perfectly reversible process requires: —
The system to be in equilibrium with its surroundings at all times.
34.
A process that involves rapid changes in pressure and temperature, leading to non-equilibrium states, is typically: —
Irreversible
35.
A process that occurs spontaneously in nature is always: —
Irreversible
36.
When a gas expands against a vacuum, the process is: —
Irreversible and entropy increases.
37.
Which type of process involves significant dissipation of energy, making it impossible to reverse without leaving a permanent change in the surroundings? —
Irreversible process
38.
Which of the following is an example of an irreversible process? —
Free expansion of a gas into a vacuum
39.
The concept of entropy increase is fundamentally linked to: —
The directionality of time
40.
The tendency for systems to move towards a state of greater disorder is a direct consequence of: —
The second law of thermodynamics
41.
The concept of 'available energy' or 'useful work' is limited by: —
The second law of thermodynamics
42.
The Kelvin-Planck statement of the second law of thermodynamics is related to: —
The impossibility of perpetual motion machines of the first kind.
43.
Which of the following is a characteristic of an irreversible process? —
There is always a dissipation of energy.
44.
The second law of thermodynamics places a fundamental limit on: —
The efficiency of converting heat into work.
45.
Which of the following statements best describes the second law of thermodynamics? —
In any spontaneous process, the total entropy of the universe increases.
46.
Which statement is true regarding irreversible processes? —
They always lead to an increase in the total entropy of the universe.
47.
In any irreversible process, the net change in entropy of the universe is: —
Positive
48.
For an irreversible process in an isolated system, the change in entropy (ΔS) satisfies: —
ΔS > 0
49.
The change in entropy (ΔS) for a reversible process is defined as: —
ΔS = Q/T
50.
Consider the free expansion of an ideal gas into a vacuum. Which of the following is true for this irreversible process? —
ΔU = 0, ΔS > 0