The rule that we will use to solve this problem is:
heat = specific heat x mass x ΔT
where:
specific heat of water = 1.0 cal/ g C
mass = 500 grams
ΔT = 10 degrees celcius
Substitute to get the heat as follows:
heat = 1 * 500 * 10 = 5000 calories
Therefore, the energy content in food is equal to 5000 cal/gram which is equivalent to 5 Cal/gram