Thermodynamics Quiz
Questions: 16 · 10 minutes
1. Two slabs have equal thickness and area and are held across the same steady temperature difference. Slab X has a higher thermal conductivity than slab Y. How do their heat-transfer rates compare?
Slab Y transfers heat faster because it provides more resistance.
Both transfer heat at the same rate because their dimensions match.
The rates cannot be compared without knowing each slab's heat capacity.
Slab X transfers heat faster because its thermal conductivity is higher.
2. For a spontaneous process occurring in an isolated system, what does the second law require?
The system's entropy must decrease.
The system's entropy cannot decrease.
The system's internal energy must increase.
The system's temperature must remain constant.
3. An ideal gas expands freely into an evacuated chamber inside a rigid, insulated container. Which outcome follows?
Its internal energy and temperature remain unchanged.
The gas cools because it performs expansion work.
Its internal energy rises because its volume increases.
Heat enters the gas to fill the empty chamber.
4. For an idealized reversible process involving a system and its surroundings, what is the total entropy change of the combined system and surroundings?
It is always positive because the system exchanges energy.
It equals the system's entropy change alone.
It is always negative because useful work is produced.
It is zero.
5. Which quantity is a state function?
Heat transferred to a system
Work performed along a process path
Enthalpy of a system
Distance traveled by a piston during a cycle
6. Which statement best expresses the Clausius form of the second law of thermodynamics?
The entropy of every individual system must remain constant.
Energy cannot be created or destroyed in an isolated system.
Two bodies in thermal equilibrium have equal internal energies.
Heat does not spontaneously flow from a colder body to a hotter body.
7. Which proposed heat engine would violate the Kelvin–Planck statement of the second law?
One that absorbs heat from a hot reservoir, produces work, and rejects some heat
One whose efficiency improves when its cold-reservoir temperature falls
One that cyclically converts all heat from a single reservoir into work
One that converts part of its heat input into work during a cycle
8. An ideal gas is compressed rapidly in a well-insulated cylinder. Which change is most likely?
Its temperature rises because work is done on the gas.
Its temperature remains constant because no heat enters.
Its temperature falls because its volume decreases.
Its internal energy becomes zero because the process is insulated.
9. A gas is heated in a rigid, sealed container. What is the pressure-volume boundary work during the heating process?
Positive because the pressure rises
Zero because the volume does not change
Negative because the container resists expansion
Equal to the increase in internal energy
10. Liquid water boils at constant pressure while heat continues to be supplied. During the liquid-to-vapor phase change, what happens to its temperature?
It falls because the vapor occupies more volume.
It rises continuously in proportion to the supplied heat.
It remains approximately constant until the phase change is complete.
It alternates between rising and falling as bubbles form.
11. A gas completes a cycle and returns to its initial thermodynamic state. What is its net change in internal energy over the entire cycle?
Zero
Equal to the net work performed
Positive whenever the gas expands during part of the cycle
Equal to the net heat absorbed
12. Objects A and B are each in thermal equilibrium with object C. What can be inferred from the zeroth law of thermodynamics?
A and B contain the same amount of internal energy.
A and B must be made of the same material.
No heat could ever flow between A and B.
A and B have the same temperature.
13. An ideal gas expands isothermally. What is its change in internal energy?
Positive, because the gas occupies a larger volume.
Zero, because an ideal gas's internal energy depends only on temperature.
Negative, because the gas performs work.
Equal to the pressure multiplied by the final volume.
14. A refrigerator removes 600 J of heat from its cold compartment while consuming 200 J of work. How much heat does it release to the room?
800 J
400 J
200 J
1,200 J
15. A reversible heat engine operates between reservoirs at 500 K and 300 K. What is its maximum theoretical efficiency?
20%
40%
60%
37.5%
16. A system absorbs 500 J of heat and performs 200 J of work on its surroundings. Using ΔU = Q − W, what is its change in internal energy?
A decrease of 300 J
An increase of 700 J
An increase of 300 J
A decrease of 700 J