P-V diagram was obtained from state 1 to state 2 when a given mass of gas is subjected to temperature change.during the process gas is...... [correct answer:heated in beginning and cooled towards end]

The internal energy of the gas at states 1 and 2 is same and equal to .
However the internal enegy is maximum at the mid point of the line and is equal to
So as the process occurs, the gas is heated until the mid point to reach the internal energy to maximum and then cooled further.