Q. Based on the first law of thermodynamics, which one of the following is correct?
A) For an isochoric process=$\mathrm{\Delta}E = - \mathcal{Q}$
B) For an adiabatic process=$\mathrm{\Delta}E = - W$
C) For an isothermal process=$\mathcal{Q = +}W$
D) For a cyclic process=$\mathcal{Q = -}W$
Explanation
(d)
(a) For isochoric process, $\mathrm{\Delta}V = 0$
$W = p\mathrm{\Delta}V = 0$
$\therefore$ $\mathrm{\Delta}E = \mathcal{Q}$
(b) For adiabatic process, $\mathcal{Q} = 0$
$\mathrm{\Delta}E = W$
(c) For isothermal process, $\mathrm{\Delta}T = 0$
and $\mathrm{\Delta}E = 0$
$\mathcal{Q = -}W$
(d) For cyclic process, state functions like
$\mathrm{\Delta}E = 0$
$\mathcal{Q = -}W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.