NCERT Class 11 Physics Chapter 12 Thermodynamics CBSE Board Sample Problems

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Question 12:

Can a system be heated and its temperature remains constant?


If the system does work against the surroundings so that it compensates for the heat supplied, the temperature can remain constant.

Question 13:

A system goes from P to Q by two different paths in the P-V diagram as shown in Fig. 12.8. Heat given to the system in path 1 is . The work done by the system along path 1 is more than path 2 by . What is the heat exchanged by the system in path 2?

P-V diagram

P-V Diagram

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Question 14:

If a refrigerator’s door is kept open, will the room become cool or hot? Explain.


Here heat removed is less than the heat supplied and hence the room, including the refrigerator (which is not insulated from the room) becomes hotter.

Question 15:

Is it possible to increase the temperature of a gas without adding heat to it? Explain.


Yes. When the gas undergoes adiabatic compression, its temperature increases.


In compression, work is done on the system So,

So internal energy of the gas increases, i.e. its temperature increases.

Question 16:

Air pressure in a car tyre increases during driving. Explain.


During driving, temperature of the gas increases while its volume remains constant.

So according to Charle’s law, at constant .

Therefore, pressure of gas increases