Question

An ideal gas is expanded from `(p_(1),V_(1),T_(1))` to `(p_(2),V_2,T_(2))` under different conditions. The correct statement(s) among the following is (are).
A. The work done on the gas is maximum when it is compressed irreversibly from `(p_(2)V_(2))` to `(p_(1),V_(1))` against constant pressure `p_(1)`
B. The work done on the gs is less when it is expanded reversibly from `V_(1)` to `V_(2)` under isothermal conditions.
C. The change in internal energy of the gas (i) zero, if it is expanded reversibly with `T_(1)=T_(2)`, and (ii) positive, if it is expanded reversible under adiabatic conditions with `T_(1) ne T_2`
D. If the expansion is carried out freely, it is simultaneously both isothermal as well as adiabatic.

Answer 1

Correct Answer - A::B::D

Work done=Area under the curve
`thereforew_(rev) lt w_(irr)`

`w_(AtoB) gt w_(AtoC)`
(d) For free expansion w=0 (free expansion)
For adiabatic process q=0 (Adiabatic)
`therefore` From first law `DeltaU=q+w`
`DeltaU=0`
i.e., `DeltaT=0` (Isothermal)