17) When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an isothermal process, A) W = 0 B) Q = 0 C) ΔU = 0 D) none of the above 18) When the first law of thermodynamics, Q = ΔU + W, is applied to an ideal gas that is taken through an adiabatic process, A) Q = 0. B) ΔU = 0. C) W = 0. D) none of the above 19) The process shown on the PV diagram is an A) isometric expansion. B) adiabatic expansion. C) isobaric expansion. D) isothermal expansion.