An insulated rigid tank contains a saturated liquid-vapor mix of water initially at a pressure of 100 kPa. The mass of the mixture is 5 kg, but only 75.6 $\%$ of the total mass is liquid. An electric resistance heater is turned on within the tank until all the water has vaporized. The heater power is a constant 2 kW.

a) What is the volume of the container? $\displaystyle \text{m}^3$

b) How long was the heater on? minutes