Question

Which describes the temperature changes that would be observed as ice at −15 degrees Celsius is changed to water at zero degrees Celsius?
Answer

steady increase in temperature from −15°C to 0°C with gradual change from ice to water

gradual increase in temperature of ice from −15°C to 0°C, holding at 0°C as ice melts to water

steady decrease in temperature from water at 0°C to ice at −15°C

holding at −15°C as ice melts to liquid water and then gradual warming of water to 0°C