`P - V` diagram of a cyclic process `ABCA` is as shown in Fig. Choose the correct alternative

Options

A. `DeltaQ_(A)rarr_(B)` is negative
B. `DeltaU_(B)rarr_(C)` is positive
C. `DeltaU_(C)rarr_(A)` is negative
D. `DeltaW_(CAB)` is negative

Answer

A, B, D

Explanation

During process `A and B` , pressure and volume both are decreasing. Therefore, temperature and hence internal energy of the gas will decrease
`(TalphaPV) or DeltaV_(A)rarr_(B)=` negative. Further, `DeltaW_(A)rarr_(B)` is negative.
In process B to C, pressure of the gas is constant while volume is increasing. Hence, temperature should increase or `DeltaU_(B)rarr_(C)` positive. During `C` to `A` volume is constant while pressure is increasing.
Therefore, temperature and hence internal energy of the gas should increase off `DeltaU_(C)rarr_(A)` positive. During process `CAB` , volume of the gas in decreasing. Hence, work done by the gas is negative.