Question

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

• A. $\Delta U=0,Q=0,w\ne 0$ and $\Delta H\ne 0$
• B. $\Delta U\ne 0,Q\ne 0,w\ne 0$ and $\Delta H\ne 0$
• C. $\Delta U=0,Q\ne 0,w=0$ and $\Delta H\ne 0$
• D. $\Delta U=0,Q\ne 0,w\ne 0$ and $\Delta H\ne 0$

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 $\Delta U=Q+W$
$\Delta U=0\Rightarrow Q\ne 0$
and $W\ne 0$
$\therefore$ Parameters are
$\Delta U=0,Q\ne 0;W\ne 0$
and $\Delta H=0$