Question

A diatomic gas `(gamma=1.4)` does 2000J of work when it is expanded isobarically. Find the heat given to the gas in the above process (in kJ).
A. 7000
B. 7
C. 5000
D. 5

Answer 1

Correct Answer - B
For a diatomic gas, `C_(v)=(5)/(2)R` and `C_(v)=(7)/(2)R`
The work done is an isobaric procers is
`W=p(V_(2)-V_(1))=nRT_(2)-nRT_(1)` or `T_(2)-T_(1)=(W)/(nR)`
The heat given in an isobaric process is `Q=nC_(p)`
`(T_(2)-T_(1))=nC_(p)(W)/(nR)=(7)/(2)`
`W=(7)/(2)xx2000J=7000J=7kJ`