While deciding the unit for heat, which temperatures interval is chosen? Why?

^{o}C-15.5^{o}C.

We know that the amount of heat released or absorbed by a body is given as `DeltaQ = msDeltaT`

Now, we also know that one calorie is defined as the amount of heat required to raise the temperature of 1 g of water through 1^{o}C. Thus, for 1 calorie of heat energy, the specific heat capacity of water should be 1 cal g^{-1} ^{o}C^{-1}. It is found experimentally that the specific heat capacity of water is 1 cal g^{-1} ^{o}C^{-1 }when the temperature range is 14.5^{o}C-15.5^{o}C.