HSSC-I (Class-11) Solved Physics MCQs; Unit-10: Thermodynamics (Baluchistan Textbook Board, Quetta) With Verified Answers 


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 some time 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 a 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 its surroundings.


8. First law of thermodynamics is based on the 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 OK
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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