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

Explanation

While deciding the unit for heat, temperature interval chosen is `14.5^@C " to "15.5^@ C`
Reason:
When 1 kg of water is heated through `1^@C` in various temperature ranges, the amount of heat required to raise temperature by `1^@C` varies slightly from range to range. Hence, it is essential to define a specific temperature range while defining unit of heat.