Calculating Work Done by Indicator Diagram

A closed bottle contains some liquid. We shake bottle vigorously for some time. It is found that temperature of liquid is increased (neglect expansion on heating). If $Q, \Delta U$ and $W$ represent heat, change in internal energy and work done, then

A cyclic process $ABCDA$ is shown in figure.

Which of the following statements is correct?

An ideal monatomic gas undergoes process $A\to B\to C$ as shown. Find efficiency of the thermodynamic cyclic shown in figure.

Consider the $P-V$ diagram shown in figure, value of work done by gas is given by

In the given elliptical $P-V$ diagram

A sample of gas is going through cyclic process, work-done by gas is

Select the incorrect statement.