Question

which coantains more heat 1kg of ice or 1kg of water both at 0 degrees Celsius

Answer 1

1kg of water contains more heat than 1kg of ice.

Enthalpy (i.e. heat) of water = Enthalpy of ice + latent heat

Latent heat is heat required to change​ the phase of the substance. In this case, latent heat is heat required to melt 1kg of ice at 0°C. Latent heat just changes the state/phase of the substance without changing it's temperature.

Hence, 1kg of water has more heat than 1kg of ice at 0°C