An iron rod of mass 2 kg and at a temperature of 280°C is dropped into some quantity of water initially at a temperature of 30°C. If the temperature of the mixture is 70°C, calculate the mass of the water. (Neglect heat losses to the surroundings) [Specific heat capacity of iron = 460 Jkg\(^{-1}\)K\(^{-1}\)] [Specific heat capacity of water = 4200 Jkg\(^{-1}\)K\(^{-1}\)]