Q.

One mole of an ideal gas in initial state A undergoes a cyclic process ABCA, as shown in the figure. Its pressure at A is P0. Choose the correct option(s) from the following.                         [2010]

1 Internal energies at A and B are the same.  
2 Work done by the gas in process AB is P0V0ln4    
3 Pressure at C is P04    
4 Temperature at C is T04    

Ans.

(1, 2)

Process A to B

Here, TA=TB    UA=UB

Also P0V0=PB×4V0

PB=P04

Work done

WAB=nRT0loge(4V0V0)

=P0V0loge4    [P0V0=nRT0]

The process BC is not clear. Therefore no judgement can be made at C regarding P and T.