Question

A fixed mass of gas undergoes the cycle of changes represented by PQRSP as shown in Figure. In some of the charges, work is done on the gas and in others, work is done by the gas. In which pair of the changes, work is done on the gas

• A. PQ and RS
• B. PQ and QR
• C. OR and RS
• D. RS and SP

Answer 1

The correct option is D RS and SP

The graph here represents

1.curve PQ- A reversible isothermal gas expansion process. In this process, the ideal gas in the system absorbs Q amount heat from a heat source at a high temperature T, expands and does work on surroundings.

2.curve QR.- A reversible adiabatic gas expansion process. In this process, the system is thermally insulated. The gas continues to expand and do work on surroundings, which causes the system to cool to a lower temperature, T.

3.curve SR... A reversible isothermal gas compression process. In this process, surroundings do work to the gas at T, and causes a loss of heat, Q.

4.SP....-A reversible adiabatic gas compression process. In this process, the system is thermally insulated. Surroundings continue to do work to the gas, which causes the temperature to rise back to T.

Hence only in Curve RS And SP the work done is on gas.