
In the process $A \rightarrow B$
Pressure is constant.
$P V=n R T$
So $V \propto T$
and volume is increasing so temperature also increases.

$I.$ Area $ABCD =$ Work done on the gas
$II.$ Area $ABCD =$ Net heat absorbed
$III.$ Change in the internal energy in cycle $= 0$
Which of these are correct
$V\propto {T^{\frac{2}{3}}}$ $[R = 1.99\ cal/mol-K]$
