Answer:
670400 J 
Step-by-step explanation:
m = mass of water = 2 kg 
T₀ = initial temperature of water = 20 ºC 
T = initial temperature of water = 100 ºC 
c = heat capacity of water = 4190 J /kg ºC
Q = energy needed to raise the temperature of water
Energy needed to raise the temperature of water is given as 
Q = m c (T - T₀)
Inserting the values
Q = (2) (4190) (100 - 20)
Q = 670400 J