Based on the first law of thermodynamics, which one of the following is correct ?

Options

A. For an isochoric process `=Deltau=-q`
B. For an isochoric process `=Deltau=-w`
C. For an isothermal process `=q=+w`
D. For a cyclic process : `q=-w`

Answer

D

Explanation

(a) For an isochoric process,
work done by the gas `=-PDeltaV`
`Deltau=q+w`
`Deltau=q-PDeltaV`
when `DeltaV=0,Deltau=q` or `qv`
(b) For an adiabatic process, `q=0,Deltau=w`
(c ) For an isothermal process, `Deltay=0,1=-w`
(d) For a cyclic process, `Deltau=0`
`:.q=-w`