Question

Why ice at 0°C has greater cooling effect than water at 0°C?

Answer 1

Ice at0°C has less heat then equal to its latent heat of fusion (3.34×10 to the power 5) kg than water at 0°C. So, ice at 0°c more effective in cooling than water at the same temperature.
Remember this also latent heat of vapourisation (2.26×10 to the power 6) kg.