2 kg of ice at `-20^(@)C` is mixed with 5kg of water at `20^(@)C`. The water content of the final mixture is (Latent heat of ice `="80 kcal kg"^(-1)`, the specific heat of water `="1 kcal kg"^(-1).^(@)C^(-1)` and specific heat of ice `="0.5 kcal kg"^(-1).^(@)C^(-1)`)

Explanation

`H=-K.2pirl(dT)/(dr)`
`int_(R_(1))^(R_(2))(Hdr)/(2pirl)=-Kint_(T_(1))^(T_(2))dT`
`H=(2pilk(T_(1)-T_(2)))/(ln((R_(2))/(R_(1))))`
`H_(i)=H_(f)`
`thereforen=4`