A sample of an ideal gas is taken through the cyclic process ABCA as shown in figure. It absorbs, 40 J of heat during the part AB, no heat during BC and rejects 60 J of heat during CA. A work of 50 J is done on the gas during the part BC. The internal energy of the gas at A is 1560 J. The workdone by the gas during the part CA is :

Options

A. 20 J
B. 30 J
C. `-30` J
D. `-60` J

Answer

B

Explanation

For cycle process
Total heat `W_("total"+Deltav)`
`-60+40+0=W_(CA)+W_(AB)+W_(BC)`
`-20=W_(CA)+0+30`
`W_(CA)=-50`.