Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: The work of expanding a gas (W): 
 Options:  <1> It is a state function. <2> Equivalent to the heat associated with the process (Q). <3> Against constant pressure it is calculated with W = -Pext ΔV. <4> In a reversible isothermal process it is calculated with W = -nRTΔV. <5> Equivalent to the internal energy change during the process (ΔU)
