A Carnot engine takes `3xx10^6` cal of heat from a reservoir at `627^@C` and gives it to a sink at `27^@C`. The work done by the engine is:

Options

A. zero
B. `16.8xx10^(6)J`
C. `8.4xx10^(6)J`
D. `4.2xx10^(6)J`

Answer

C

Explanation

For a carnot engine
`Q_(1)/Q_(2)=T_(1)/T_(2)=(627+273)/(27+273)=900/300=3/1`
`thereforeQ_(2)=Q_(1)/3=(3xx10^(6))/3=10^(6)cal`
`therefore` Work done `=Q_(1)-Q_(2)=2xx10^(6)cal`
`=2xx10^(6)xx4.2J`
`=8.4xx10^(6)J`