1.  A pupil put 2 litres of water at 20 °C into her 1000 W kettle. She switched it on and then forgot it for 15 minutes. Unfortunately, it did not have an automatic cut-out and when she came back the kitchen was full of steam. 1 litre of water has a mass of 1 kg.

a)  How much energy was required to bring the water to boiling point?

b)  How much electrical energy had been used altogether?

c)  How much water had been turned into steam?

d)  Which of your answers are approximate and why?