Question

For an adiabatic free expansion of an ideal gas, which of the following is true?

• A. $q=0$, $w=0$, $\Delta U=0$
• B. $q=0$, $w=+ve$, $\Delta U=-ve$
• C. $q=0$, $w=+ve$, $\Delta U=+ve$
• D. $q=+ve$, $w=0$, $\Delta U=-ve$

Answer 1

The correct option is A $q=0$, $w=0$, $\Delta U=0$

$\Delta U=q+w$
For a free expansion work done is zero, since the external pressure is zero.

For an adiabatic process, $q=0$
Hence, from first law $\Delta U=0$