Arigid (constant volume) tank sealed by a valve initially contains 100 kg of air at a pressure of 100 kpa and 300 k. at time = 0, the valve for the air tank is opened in a controlled manner and air leaks out isothermally (constant temperature) of the tank at a constant mass flow rate of 1 kg/s. the valve is closed after 75 seconds. answer the following questions using the mass values calculated previously for the problem from lecture 3: a. the total change in internal energy of the air tank, in kj, if the specific internal energy for air is 214.1 kj/kg. b. the heat transfer of the process, in kj, if kinetic and potential energies are neglected and the specific enthalpy for air at 300 °c is 300.1 kj/kg.