The correct option for free expansion of an ideal gas under adiabatic condition is:

The correct option for free expansion of an ideal gas under adiabatic condition is:
A $q=0,\ \Delta T0$
B $q<0,\ \Delta T=0$ and $w=0$
C $q>0,\ \Delta T>0$ and $w>0$
D $q=0,\ \Delta T=0$ and $w=0$

Detailed Solution

Free expansion: $P_{ext} = 0 \Rightarrow w = -P_{ext}\Delta V = 0$ Adiabatic process: q = 0 $\Delta U = q + w = 0$; since the internal energy of an ideal gas depends only on temperature, $\Delta T = 0$. So q = 0, $\Delta T$ = 0 and w = 0.

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