One mole of H2 at 300 K takes a volume of 10 lits in a cylinder fitted with a piston. It is expanded isothermally to 20 lits. Consider ideal behavior for the gas, determine W, Q, ΔE, ΔH, if the expansion is taken out (i) reversibly, (ii) against a constant external pressure of 0.1 atm., (iii) against zero external pressure (vacuum).