p-T diagram of one mole of an ideal monatomic gas is shown. Processes AB and CD are adiabatic. Work done in the complete cycle is

Options

A. (a) `2.5RT`
B. (b) `-2RT`
C. (c) `1.5RT`
D. (d) `-3.5RT`

Answer

A

Explanation

`Q_(n et) =W_(n et)`
`Q_(AB)=Q_(CD)=0`
`Q_(BC)=nC_pDeltaT=(1)(5/2R)(4T-T)`
`=7.5RT`
`Q_(DA)=nC_pDeltaT`
`=(1)(5/2R)(3T-5T)`
`=-5RT`
`:.` `W_(n et)=Q_(n et)=7.5RT-5RT`
`=2.5RT`