Steam at $0\mathrm{.}9$MPa and dryness fraction $0\mathrm{.}86$ expands in a cylinder behind a piston isothermally and reversibly to a pressure of $0\mathrm{.}05$MPa and temperature of $250C.$ Calculate:

$3\mathrm{.}1.$ Change of internal energy.

$3\mathrm{.}2.$ Change of enthalpy per kg of steam.

$3\mathrm{.}3.$ Change of entropy.

$(5)$

$3\mathrm{.}4.$ The heat supplied during the process is found to be $560k\frac{J}{k}g,$ calculate the work done per kilogram of steam.

$(3)$