Free Thermodynamics MCQs with Answers
714 Thermodynamics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Thermal equilibrium and heat explain how temperature and energy transfer are related, while molar specific heats describe the heat required by a gas at constant volume or constant pressure. The first law connects heat supplied, work done and change in internal energy, with sign conventions kept distinct from temperature changes.
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Read the Thermodynamics notesFree MDCAT chapter notes with key terms714 questions · page 20 of 36
- A. Temperature
- B. Pressure
- C. Entropy
- D. Energy Conservation
Explanation: The prefix "iso-" means "same" or "constant," and "thermal" relates to heat or temperature.
Correct answer: Temperature- A. 6.68 × 10⁵ J
- B. 6.68 x 10⁵ kJ
- C. 668 J
- D. 6688 kJ
Explanation: The heat required for a phase change is given by Q = mL, where m is the mass and L is the specific latent heat.
Correct answer: 6.68 × 10⁵ J- A. 1260 W
- B. 12.6 kW
- C. 210 W
- D. 12.6 W
Explanation: First, find the heat energy required: Q = mcΔT = (500 g) × (4.2 J/g°C) × (50°C - 20°C) = 63,000 J.
Correct answer: 210 W- A. 28 min
- B. 16.7 min
- C. 2.8 min
- D. 167 min
Explanation: First, calculate the total heat needed: Q = mL = (50 g) × (334J/g) = 16,700 J. The heater provides power (P) of 100 W, which is 100 J/s.
Correct answer: 2.8 min- A. 62 min
- B. 62 sec
- C. 1.5 hour
- D. 0.5 hour
Explanation: First, calculate the total heat energy required: Q = mL = (500 g) × (2230 J/g) = 1,115,000 J. The heater power (P) is 300 W (300 J/s).
Correct answer: 62 min- A. Coefficient of linear expansion
- B. Coefficient of volume expansion
- C. Ideal gas constant
- D. Specific heat of a substance
Explanation: The law of heat exchange states that heat lost by the hot body = heat gained by the cold body.
Correct answer: Specific heat of a substance- A. 1 K
- B. 100 K
- C. 273.16 K
- D. 0 K
Explanation: The triple point of water is the specific temperature and pressure where water can coexist in solid, liquid, and gaseous phases.
Correct answer: 273.16 K- A. Isothermal
- B. Adiabatic
- C. Isovolumetric
- D. Isobaric
Explanation: An isothermal process is a thermodynamic process in which the temperature of a system remains constant (ΔT = 0).
Correct answer: Isothermal- A. 98.6º
- B. 40º
- C. 37º
- D. 459.4º
Explanation: The normal human body temperature is approximately 37°C on the Celsius (centigrade) scale.
Correct answer: 37º- A. Zeroth law of thermodynamics
- B. Second law of thermodynamics
- C. First law of thermodynamics
- D. Third law of thermodynamics
Explanation: The Zeroth Law of Thermodynamics establishes the concept of thermal equilibrium.
Correct answer: Zeroth law of thermodynamics- A. Heat and surrounding
- B. Heat and other forms of energy
- C. Heat and liquid
- D. Heat and chemical energy
Explanation: Thermodynamics is the branch of physics that deals with the relationships between heat, work, and temperature, and their relation to…
Correct answer: Heat and other forms of energy- A. Positive
- B. Negative
- C. Zero
- D. Infinite
Explanation: For a reversible process, the total entropy change of the universe (system + surroundings) is zero, as entropy gained by the system is…
Correct answer: Zero- A. 5
- B. 6
- C. 4
- D. 3
Explanation: The COP of a refrigerator is given by COP = Tcold / (Thot - Tcold ), where Tcold = 250 K and Thot = 300 K.
Correct answer: 5- A. 5000 J
- B. 10000 J
- C. 2000 J
- D. 2500 J
Explanation: Heat required is Q = m·c·ΔT, where m = 2 kg, c = 500 J/kg·°C, and ΔT = 10°C. Thus, Q = 2 × 500 × 10 = 10,000 J.
Correct answer: 10000 J- A. Constant pressure
- B. Constant volume
- C. Constant temperature
- D. Constant entropy
Explanation: In Carnot cycle, the isothermal expansion occurs at constant temperature, where the gas absorbs heat from a reservoir and expands while…
Correct answer: Constant temperature- A. Isothermal
- B. Isobaric
- C. Isochoric
- D. Impossible
Explanation: For an ideal gas (PV = nRT), constant temperature and pressure imply constant volume, which contradicts process with changing state.
Correct answer: Impossible- A. Carnot cycle
- B. Otto cycle
- C. Diesel cycle
- D. Rankine cycle
Explanation: The Carnot cycle provides the maximum possible efficiency for a heat engine operating between two given temperatures, as it consists of…
Correct answer: Carnot cycle398. The latent heat of fusion of ice at 0°C is 334 kJ/kg. The entropy change when 1 kg of ice melts is:
- A. 1226 J/K
- B. 334 J/K
- C. 1000 J/K
- D. 273 J/K
Explanation: Entropy change for a phase transition is ΔS = ΔH/T, where ΔH = 334 kJ/kg = 334,000 J/kg and T = 0°C = 273 K.
Correct answer: 1226 J/K- A. Heat is removed from the system
- B. Work is done on the system
- C. Heat is added at constant temperature
- D. Temperature decreases
Explanation: Entropy change is ΔS = Q/T for a reversible process at constant temperature.
Correct answer: Heat is added at constant temperature- A. 400 J
- B. 600 J
- C. 300 J
- D. 1000 J
Explanation: The maximum efficiency of a Carnot engine is η = 1 - (Tcold/Thot) = 1 - (300/500) = 0.4.
Correct answer: 400 J