A hot metal block is dropped into cold water in an insulated container. Which statement is correct once thermal equilibrium is reached?
Correct answer D. Heat lost by the block equals heat gained by the water
Topic / 30 questions
Thermodynamics MCQs
Thermodynamics MCQs cover thermal equilibrium, specific and molar specific heats, work done when a gas changes volume, the first law of thermodynamics and the relation Cp − Cv = R. They help MDCAT, ECAT and FSc candidates revise concepts and short calculations, and every question on MCQs360 shows its correct answer instantly.
- Electromagnetic Induction 30
- Fluid Dynamics 30
- Electrostatics 30
- Electronics 30
- Electromagnetism 30
- Current Electricity 30
- Work and Energy 30
- Waves 30
- Vectors and Equilibrium 30
- Nuclear Physics 30
- Dawn of Modern Physics 30
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- Atomic Spectra 30
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- Force and Motion 30
A gas is taken through a complete cycle and returns to its initial state. Which statement is correct?
Correct answer D. The net heat absorbed equals the net work done by the gas
Which of the following is a state function of a thermodynamic system?
Correct answer A. Internal energy
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The internal energy of a fixed mass of an ideal gas depends only on its ____.
Correct answer A. temperature
3.0 mol of an ideal gas is heated at constant pressure through 20 K. How much work does the gas do (R = 8.31 J mol⁻¹ K⁻¹)?
Correct answer A. 5.0 × 10² J
How much heat is needed to raise the temperature of 2.0 mol of an ideal gas by 10 K at constant pressure (Cp = 29.1 J mol⁻¹ K⁻¹)?
Correct answer D. 5.8 × 10² J
A gas is compressed adiabatically and 600 J of work is done on it. What is the change in its internal energy?
Correct answer B. +600 J
When an ideal gas expands adiabatically, its temperature ____.
Correct answer C. falls, because work is done at the expense of internal energy
During an isothermal expansion of an ideal gas, which statement is correct?
Correct answer B. The heat absorbed equals the work done by the gas
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A gas in a cylinder at a constant pressure of 1.0 × 10⁵ Pa pushes a piston of area 0.020 m² outwards through 0.15 m. What work is done by the gas?
Correct answer D. 300 J
400 J of work is done on a gas while it gives out 150 J of heat. What is the change in its internal energy?
Correct answer D. +250 J
A gas absorbs 800 J of heat and does 300 J of work on its surroundings. What is the change in its internal energy?
Correct answer A. +500 J
The first law of thermodynamics is essentially a statement of ____.
Correct answer A. the law of conservation of energy
On a pressure–volume graph, the work done by a gas during an expansion is equal to ____.
Correct answer B. the area under the curve between the initial and final volumes
How much work is done by a gas during a process in which its volume remains constant?
Correct answer B. Zero
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A gas expands at a constant pressure of 2.0 × 10⁵ Pa from 1.5 L to 4.0 L. How much work does the gas do?
Correct answer B. 500 J
When an ideal gas is heated at constant volume, the heat supplied is used ____.
Correct answer A. entirely to increase its internal energy
In deriving Cp − Cv = R, the work done by one mole of an ideal gas heated through 1 K at constant pressure is shown to equal ____.
Correct answer B. R
For a monatomic ideal gas Cv = 3R/2. What is the value of γ = Cp/Cv?
Correct answer C. 1.67
A certain ideal gas has a molar specific heat at constant volume of 20.8 J mol⁻¹ K⁻¹. What is its molar specific heat at constant pressure (R = 8.31 J mol⁻¹ K⁻¹)?
Correct answer A. 29.1 J mol⁻¹ K⁻¹
About Thermodynamics MCQs
Questions start with thermal equilibrium and the direction of heat flow from a hotter to a colder body. They compare specific heat per kilogram with molar specific heat and ask you to convert between them using molar mass. Work done by a gas is found from W = PΔV, including the special case of a constant-volume process. The first law of thermodynamics is applied to find changes in internal energy from heat supplied and work done, and the unit closes with the derivation and use of Cp − Cv = R for an ideal gas.
Key facts to remember
- First law of thermodynamics: Q = ΔU + W, where W is the work done by the gas; it is a statement of conservation of energy.
- Work done by a gas at constant pressure is W = PΔV, which equals nRΔT for an ideal gas; at constant volume W = 0.
- For an ideal gas, Cp − Cv = R, where R = 8.314 J mol⁻¹ K⁻¹.
- Molar specific heat equals specific heat multiplied by molar mass: C = cM.
- Two bodies are in thermal equilibrium when they are at the same temperature, so no net heat flows between them.
Exams that include Thermodynamics MCQs
Pakistan
- MDCAT
- ECAT (UET)
- NUMS
- AKU
- FSc boards
India
- NEET
- JEE Main
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Thermodynamics MCQs
- Fix one sign convention for the first law and stick to it: heat added is positive and work done by the gas is positive.
- Remember that Cp is greater than Cv because at constant pressure some heat goes into doing work.
- When converting molar specific heat to specific heat, change grams per mole to kilograms per mole first.
- Practise the constant-volume, constant-pressure and isothermal cases side by side to see what is zero in each.
Frequently asked questions
Which exams ask Thermodynamics MCQs?
Thermodynamics is part of the FSc physics syllabus, so its MCQs appear in MDCAT, ECAT (UET), NUMS and AKU entry tests and in FSc board papers. Students in India meet the same ideas in NEET and JEE Main, and Bangladeshi students in HSC and the medical admission test.
Why is Cp greater than Cv for a gas?
At constant volume all the heat supplied raises the internal energy of the gas. At constant pressure the gas also expands and does work on its surroundings, so more heat is needed for the same temperature rise. For one mole of an ideal gas the difference is exactly R.
Last reviewed October 2026