Question

Which one of the following equations does not correctly
represent the first law of thermodynamics for the given
processes involving an ideal gas? (Assume non-expansion
work is zero)

(a) Adiabatic process : AU = --W
(b) Isochoric process : AU = 9
(c) Isothermal process : a = --W
(d) Cyclic process : a = -W

Mains (April 2019)​

Answer 1

Answer

(a) Adiabatic process : ∆U = - w

★Explanation★

According to first law of thermodynamics ∆U = q + w

For adiabatic process , q = 0 ; ∆U = w

For isochoric process, v = 0 ; w = 0 thus, ∆U = q

For isothermal process ∆U = 0 thus

q = -w

For cyclic process ∆U = 0 thus

q = -w