Question

Which of the following is not correct for an ideal gas as per first low of thermodynamics?

• A. Adiabatic $\mathrm{\Delta U}=-\mathrm{w}$
• B. Isothermal $\mathrm{q}=-\mathrm{w}$
• C. cyclic $\mathrm{q}=-\mathrm{w}$
• D. Isochoric $\mathrm{\Delta U}=\mathrm{q}$

Answer 1

The correct option is A

Adiabatic $\mathrm{\Delta U}=-\mathrm{w}$

Explanation for the correct option:-

1. For Adiabatic process, $\mathrm{q}=0$ $\therefore \mathrm{\Delta U}=\mathrm{w}$
2. In the given option the value of $W$ is given in negative but in the correct formula as per first law of thermodynamic the value of $W$ is in positive.
3. From 1^st Law, $∆U=q+W$
4. $Inadiabatic,q=0,Therefore,∆U=W$

Hence, Option A is the correct option.