A vessel containing 100 g ice at `0^(@)C` is suspended in a room where temperature is `35^(@)C`. It was found that the entire ice melted in 10 hour. Now the same vessel containing 100 g of water at `0^(@)C` is suspended in the same room. How much time will it take for the temperature of water to rise to `0.5^(@)C`. Neglect the heat capacity of the vessel. Specific heat of water and specific latent heat of fusion of ice are `1 cal g^(-1) .^(@)C^(-1)` and `80 cal g^(-1)` respectively.