Answer:
Well, let's see. Water at room temperature has a heat capacity of 4.18 J/g-C, and water also has a density of 1g/mL. If there's one litre of water, there's 1000 g of water. If the change in temperature is 1 C, and there are 1000 g of water, and specific heat capacity's 4.18...
Q = mcT
Q = (1000g)(4.18J/g-C)(1 C)
Q = 4180 J
So you need 4180 J of heat.
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The definition of one calorie is as stated in the question. One calorie is equivalent to 4.18 Joules.
Not sure where the maths went wrong but just so you know.