Question

Ice at 0 degree Celsius appears colder to the mouth than water at 0degree Celsius,why?

Answer 1

Because when ice changes to water it absorbs some heat as latent heat which breaks the intermolecular forces but doesn't change the temperature so definitely ice will be colder than water at 0degree celcius

Answer 2

Ice at zero degree Celsius appears colder to the mouth than water at zero degree Celsius because phase change.

Explanation:

The substance temperature changes by heating the substance. The temperature of substance remains constant during phase transition of substance.

For example: if we increase the temperature of water, it  will continue to increase until it reaches 100°C and then it will not rise until all the water becomes steam.

To achieve your body temperature, ice absorbs latent heat as well as heat energy in your mouth, whereas water at  0°C only absorbs heat energy to reach your body temperature.  

Thus, water absorbs only  less amount  of body's heat energy than ice. That's why ice has a colder feeling.