Which of the following statements MUST BE TRUE if a reaction is spontaneous at room temperature? Each correctly assigned choice earns 0.25 marks. The change in free energy must always be negative. When heat is released (i.e., when enthalpy decreases in the system), the change in entropy in the system must always be positive. The change in the entropy of the system must always be positive. When heat is absorbed (i.e., when enthalpy in the system increases), the change in entropy in the system must always be positive