Question

Which among the following is a feature of adiabatic expansion?

• A. $\Delta V<0$
• B. $\Delta U<0$
• C. $\Delta U>0$
• D. $\Delta T=0$

Answer 1

Answer: (B)

$\Delta U<0$

For adiabatic expansion, $Q=0$

For expansion, final volume is greater than initial volume which implies $\Delta V>0$

$\therefore$ work done $=-P\Delta V<0$

Therefore, $\Delta V=Q+W$ is negative.

i.e. $\Delta U<0\Rightarrow$ for adiabatic expansion.