If a chamber is heated through an electric heater whose resistance varies with time as R = 50(1 + 2t) ohm, where ‘t’ is time in seconds. The current 100 A is supplied to the heater for 10 seconds. If the system and its boundary is defined as shown in the figure below (heater is the part of the system).

If the specific heat of the gas at constant pressure and constant volume is given as 1.005 kJ/kg.K and 0.718 kJ/kg.K respectively. Then the change in internal energy of the gas is ______kJ.