When water of mass m at 80degree Celsius is added to 2kg of ice at calorimeter, all just melts to form water at 0degree Celsius then m is.....kg

dear student,
Apply principle of calorimetry here
Heat lost by water at 80 deg in cooling down to 0 deg= heat gained by ice at 0 deg to change to water at 0 deg.
mass of water* specific heat of water * change in temperature of water= mass of ice* Latent heat of fusion of ice