Question

For isothermal expansion of an ideal gas, the correct combination of the thermodynamic parameters will be

• A. $ΔU = 0, Q=0, w ≠ 0$ and $ΔH ≠ 0$
• B. $ΔU ≠ 0, Q≠0, w ≠ 0$ and $ΔH ≠ 0$
• C. $ΔU = 0, Q≠0, w = 0$ and $ΔH ≠ 0$
• D. $ΔU = 0, Q≠0, w ≠ 0$ and $ΔH ≠ 0$

Answer 1

Answer: (D)

For isothermal expansion of an ideal gas
$\Delta T=0$
From $\Delta U=n C _{v} \Delta T$,
$\Delta U=0$ and, from
$\Delta H=n C _{\rho} \Delta t=0$
From first law of thermodynamics,
as $\Delta U=Q+W$
$\Delta U=0 \Rightarrow Q \neq 0$
and $W \neq 0$
$\therefore $ Parameters are
$ \Delta U=0, Q \neq 0 ; W \neq 0 $
and $\Delta H=0 $