According to the second law of thermodynamics, for any process that may occur within an isolated system, which one of the choices applies?

In an isochoric process, the internal energy of a system decreases by 50 J. What is the work done?

In an isothermal process, there is no change in:

A fixed mass of an ideal gas slowly releases 1500 J of heat and as a result contracts slowly, at a constant pressure of 2.0 x 10⁴ Pa, from a volume of 0.050 m³ to 0.025 m³ . What is the effect on the internal energy of the gas?

When the first law of thermodynamics, Q = DU + W, is applied to an ideal gas that is taken through an isobaric process