One mole of an ideal gas (C_p=7R/2) in a closed piston/cylinder is expanded from Tⁱ = 700 K, Pⁱ = 0.75 MPa to P^f = 0.1 MPa by the following pathways. For each pathway, calculate ΔU, ΔH, Q, and W_EC: 

(a) Isothermal; 

(b) Constant volume; 

(c) Adiabatic.