11th Physics MCQs Preparation 2022 and Onwards (Unit: Thermodynamics: Set-1 (30 MCQs)) for National MDCAT,, ECAT, FPSC, PPSC, JOB Exam, Physics Lecturer, SSC, HSSC (F.Sc.), BS, MS Exams NTS, ETS, etc.



1. When two bodies are made at thermal contact having the same temperature then they are at:




... Answer is B. Thermal equilibrium
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2. Normal temperature of a human body is 98.6°F while its atmosphere temperature is 84.6°F. What will be the temperature of the dead body in such an atmosphere




... Answer is A. 84.6°Fe
After death, a body's temperature drops to about 1.5°F each hour and attains the thermal equilibrium after sometime in the place where it is kept.


3. When the system is expanded by adding heat energy then the work done is:




... Answer is C. Positive and by the system
1st law of thermodynamics


4. Which substance possesses the largest internal energy at t°C




... Answer is C. Gas
The internal energy (I.E) of a system is inversely related to the potential energy (P.E) of the molecules. Gas has small P.E so maximum I.E. Sold has maximum P.E. So least I.E


5.  Internal energy of a substance is defined in terms of




... Answer is A. P and V
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6. The ratio between work done and heat energy is equal to:




... Answer is B. Joul's constant
J = `\frac {W}{Q}` (Work and heat ratio)


7. A system that transfers neither mass nor energy is called; :




... Answer is C. Isolated system
An isolated system has no interaction with the surrounding.


8. First law of thermodynamics is based on law of conservation of




... Answer is B. Energy
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9. A process in which all the heat energy is used for increasing the internal energy of the system is known as:




... Answer is B. Isochoric
The process in which volume remains constant. ΔW= 0 so ΔQ = ΔU


10. In which process the internal energy is used for doing work:




... Answer is D. Adiabatic `
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11. Specific heat of a gas in an isothermal process is:




... Answer is A. Zero
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12. A process in which the system remains at thermal equilibrium is known as:




... Answer is C. Isothermal
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13. The value of the adiabatic constant for mono-atomic gas is;




... Answer is D. 1.66
-----------For monoatomic gases, CV = 3R/2 and CP = 5R/2 (where R is universal gas constant), ɣ = `\frac {Cp}{Cv}` = `\frac {6}{3}` = 1.667


14.  The efficiency of a heat engine will be 100% when




... Answer is D. The temperature of the cold reservoir is O K
For 100% efficiency either the HTR should be at a very much higher temperature or the LTR must be at very lower temperature


15. Second law of thermodynamics provides the proper direction of




... Answer is D. Flow of heat
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16.. A device that converts mechanical energy into heat energy is known as:




... Answer is A. Heat engine
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17. Entropy of a system in a reversible process; :




... Answer is D. Zero
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18. Entropy remains constant in the process of




... Answer is D. Adiabatic
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19. In which of the systems listed below is the entropy decreasing?




... Answer is A. A gas is cooled.
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20. If the temperature of the source and sink of a Carnot engine having efficiency η are each decreased by 100K, then the efficiency η :




... Answer is C. increases.
Let T1 = 200 K and T2 = 400 K 👉 Efficiency η% = 1 - `\ frac {T2}{T1}` x 100 = 1 - `\ frac {200 K}{400 K}`= 50% 👉 When the temperature is decrease by 100 K 👉 Efficiency η% = 1 - `\ frac {T2 - 100 K}{T1 - 100 K}` x 100 = 1 - `\ frac {200 K - 100 K}{400 K - 100 K}`= 67%


21. Assume we can change the equilibrium state of a system via two different processes. Assume that the initial and the final state are the same. Which of the quantities `\Δ_U`, ΔQ, ΔW, and ΔT must be the same for the two processes?




... Answer is B. Only ΔU and ΔT
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22. In any process the maximum amount of mechanical energy that can be converted to heat




... Answer is A. Depends upon the amount of friction
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23. In an isothermal change, internal energy




... Answer is D. remains constant
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24. A thermos bottle containing hot coffee is vigorously shaken. Consider coffee as system, then its temperature




... Answer is A. Increases
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25. Maximum work can be obtained in tie process called




... Answer is C. Isothermal
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26. A heat engine takes in 800 J of heat at 1000 K and exhausts 600 J of heat at 400 K. What is the actual efficiency of this engine?




... Answer is A. 25%
Efficiency η% = 1 - `\ frac {QL}{QH}` x 100 = 1 - `\ frac {600}{800}`= 25%


27. If the temperature of the heat source is increased, the efficiency of a Carnot's engine :




... Answer is A. Increases
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28. Triple point of water is




... Answer is D. 273.16°K
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29. A real gas can be approximated to an ideal gas at




... Answer is A. Low density
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30. If the volume of the gas is to be increased by 4 times, then




... Answer is C. At constant T the pressure must be increased by four times
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Or 

Select from below Links for HSSC-I (Class-11) :  Physics MCQS Preparation


1. Unit:  Measurements: Set-1 (32 MCQs), Set-2 (50 MCQs), Set-3 (50 MCQs),                                   Set-4 (50 MCQs),   Set-5 (50 MCQs),  

2. Unit:  Vectors and Equilibrium: Set-1 (34 MCQs), 

3. Unit:  Force and Motion: Set-1 (34 MCQs), 

4. Unit:  Work and Energy: Set-1 (29 MCQs), 

5. Unit:  Rotational and Circular Motion: Set-1 (31 MCQs), 

6. Unit:  Fluid Mechanics or Dynamics: Set-1 (31 MCQs), 

7. Unit:  Oscillations : Set-1 (27 MCQs), 

8. Unit:  Waves : Set-1 (27 MCQs), 

9. Unit:  Physical Optics : Set-1 (27 MCQs), 

10. Unit:  Thermodynamics: Set-1 (34 MCQs),  

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