A gas undergoes change in its state from position $A$ to position $B$ via three different paths as shown in Fig. Select the correct alternatives:

 

Internal energy $\left(U\right)$ depends only on the initial and final states. Hence, $∆U$ will be same in all the three paths. In all the three paths. In all the three paths, work done by the gas is positive and the product $PV$ or temperature $T$ is increasing. Therefore, internal energy is also increasing. So, from the first law of thermodynamics, heat will be absorbed by the gas. Further, area under $P – V$ graph is maximum in path $1$ while $∆U$ is same for all the three paths. Therefore, heat absorbed by the gas is maximum in path $1$. For temperature of the gas, we can see that product $PV$ first increases in path $1$ but whether it is decreasing or increasing later on we cannot say anything about it unless the exact values are known to us.