Question

In a given process on an ideal gas $dW=0$ and $dQ<0$, then for the gas :

• A. The temperature will decrease
• B. The volume will increase
• C. The pressure will remain constant
• D. The temperature will increase

Answer 1

The correct option is A The temperature will decrease

From first law of thermodynamics,

$dQ=dU+dW$

we have $dQ=dU$ $(asdW=0)$

But $dQ<0$

$\therefore dU<0$

$N{C}_V\Delta T<0$

or $\Delta T<0$

Hence, the temperature will decrease.