How much heat energy is necessary to raise the temperature of kg of water from `20" "^(@)C` to `100" "^(@)C`.

Explanation

`m=5 kg, c=1kcal/kg" "^(@)C` and change in temperature `Delta T = 100-20=80" "^(@)C`
Energy to be supplied to water = energy gained by water
= mass of water `xx` specific heat of water `xx` change in temperature of water
= =`mxxcxxDelta T`
= `5xx80" "^(@)C`
=400 kcal
Hence, the energy necessary to raise the temperature of water = 400 kcal.