# MCAT Physics Practice Test 3: Thermodynamics

### Test Information

15 questions

minutes

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1. If an object with an initial temperature of 300 K increases its temperature by 1°C every minute, by how many degrees Fahrenheit will its temperature have increased in 10 minutes?

• A. 6°F
• B. 10°F
• C. 18°F
• D. 30°C

2. Which of the following choices correctly identifies the following three heat transfer processes?

I. Heat transferred from the Sun to the Earth

II. A metal spoon heating up when placed in a pot of hot soup

III. A rising plume of smoke from a fire

• A. I. Radiation; II. Conduction; III. Convection
• B. I. Conduction; II. Radiation; III. Convection
• C. I. Radiation; II. Convection; III. Conduction
• D. I. Convection; II. Conduction; III. Radiation

3. A 20 m steel rod at 10°C is dangling from the edge of a building and is 2.5 cm from the ground. If the rod is heated to 90°C, will the rod touch the ground? (Note: α = 1.1 × 10-5 K-1)

• A. Yes, because it expands by 3.2 cm.
• B. Yes, because it expands by 2.6 cm.
• C. No, because it expands by 2.2 cm.
• D. No, because it expands by 1.8 cm.

4. What is the final temperature of a 5 kg silver pendant that is left in front of an electric heater, absorbing heat energy at a rate of 100 W for 10 minutes? Assume the pendant is initially at 20°C and that the specific heat of silver is

• A. 29°C
• B. 59°C
• C. 72°C
• D. 100°C

5. How much heat is required to completely melt 500 g gold earrings, given that their initial temperature is 25°C? (The melting point of gold is 1064°C, its heat of fusion is and its specific heat is

• A. 15 kJ
• B. 32 kJ
• C. 66 kJ
• D. 97 kJ

6. Given the cycle shown, what is the total work done by the gas during the cycle?

• A. –10 J
• B. 0 J
• C. 7.5 J
• D. 17.5 J

7. In an adiabatic compression process, the internal energy of the gas:

• A. increases because the work done on the gas is negative.
• B. increases because the work done on the gas is positive.
• C. decreases because the work done on the gas is negative.
• D. decreases because the work done on the gas is positive.

8. The entropy of a system can:

• A. never decrease.
• B. decrease when the entropy of the surroundings increases by at least as much.
• C. decrease when the system is isolated and the process is irreversible.
• D. decrease during an adiabatic reversible process.

9. A student making a coffee cup calorimeter fails to use a second coffee cup and incompletely seals the lid. What was her initial goal, and what was the result of this mistake?

• A. She was trying to create an isolated system but created an open system instead.
• B. She was trying to create an isolated system but created a closed system instead.
• C. She was trying to create a closed system but created an open system instead.
• D. She was trying to create a closed system but created an isolated system instead.

10. A certain substance has a specific heat of and a melting point of 350 K. If one mole of the substance is currently at a temperature of 349 K, how much energy must be added in order to melt it?

• A. More than 1 J
• B. Exactly 1 J
• C. Less than 1 J but more than 0 J
• D. Less than 0 J

11. Which of the following is NOT a state function?

• A. Internal energy
• B. Heat
• C. Temperature
• D. Entropy

12. The figure shown depicts a thick metal container with two compartments. Compartment A is full of a hot gas, while compartment B is full of a cold gas. What is the primary mode of heat transfer in this system?

• B. Convection
• C. Conduction
• D. Enthalpy

13. Substances A and B have the same freezing and boiling points. If solid samples of both substances are heated in the exact same way, substance A boils before substance B. Which of the following would NOT explain this phenomenon?

• A. Substance B has a higher specific heat.
• B. Substance B has a higher heat of vaporization.
• C. Substance B has a higher heat of fusion.
• D. Substance B has a higher internal energy.

14. In experiment A, a student mixes ink with water and notices that the two liquids mix evenly. In experiment B, the student mixes oil with water; in this case, the liquids separate into two different layers. The entropy change is:

• A. positive in experiment A and negative in experiment B.
• B. positive in experiment A and zero in experiment B.
• C. negative in experiment A and positive in experiment B.
• D. zero in experiment A and negative in experiment B.

15. Which of the following processes is LEAST likely to be accompanied by a change in temperature?

• A. The kinetic energy of a gas is increased through a chemical reaction.
• B. Energy is transferred to a solid via electromagnetic waves.
• C. A boiling liquid is heated on a hot plate.
• D. A warm gas is mixed with a cold gas.

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