An ideal gas is taken through the cycle `A rarr B rarr C rarr A`, as shown in figure. If the net heat supplied to the gas in the cycle is 5J, the work done by the gas in the process `C rarr A` is

Options

A. `-5 J`
B. `-10 J`
C. `-15 J`
D. `-20 J`

Answer

A

Explanation

Process `A rarr B` occurs at constant pressure,
`:. W_(AB) = Pdelta V = P(V_(2) - V_(1))`
`= 10 xx (2-1) = 10 J`
Process `B rarr C`, occurs at constant volume,
`:. W_(BC) = 0`
For a cyclic process, `Delta Q = W`
`:. Delta Q = W_(AB) + W_(BC) + W_(CA)` or `5 = 10 + 0 + W_(CA)` or `W_(CA) = - 5J`