IIT JEE Advanced 2010 Paper 2

From the graph, the work along the dotted line is irreversible isothermal process in three steps, so work done is sum of pressure– volume work done in each step.
Wd = (4 × 1.) + (1 × 1) + (2.5×

2

3

) = 8.65
The work along the solid line is reversible isothermal process, so,
Ws = 2 × 2.303 log

5.5

0.5

= 2 × 2.303 × log 11
= 2 × 2.303 × 1.0414 = 4.79

Wd

Ws

=

8.65

4.79

= 1.80 ~ 2