Question

Based on the first law of thermodynamics, which one of the following is correct?

• A. For an isochoric process, $\text{ΔE} \, \text{=} \, - \text{q}$
• B. For an adiabatic process, $\text{ΔE} \, \text{=} \, - \text{w}$
• C. For an isothermal process, $\text{q} = \text{W}$
• D. For a cyclic process, $\text{q} = - \text{W}$

Answer 1

Answer: (D)

(a) For isochoric process, $\text{ΔV} \, \text{=} \, \text{0}$

$\text{W} \, \text{=} \, \text{pΔV} \, \text{=} \, \text{0}$

$\therefore \, \text{ΔE} \, \text{=} \, \text{q}$

(b) For adiabatic process, $q=0$

$\text{ΔE} \, \text{=} \, \text{W}$

(c) For isothermal process, $\text{ΔT} \, \text{=} \, \text{0}$

and $\text{ΔE} \, \text{=} \, \text{0}$

$\text{q} \, \text{=} \, - \text{W}$

(d) For cyclic process, state functions like

$\text{ΔE} \, \text{=} \, \text{0}$

$\text{q} \, \text{=} \, - \text{W}$