45 g of water at 50°C in a beaker is cooled when 50 g of copper at 18°C is added to it. The contents are stirred till a final constant temperature is reached. Calculate the final temperature. The specific heat capacity of copper is 0.39 J g^-1 K^-1 and that of water is 4.2 J g^-1 K^-1. State the assumptions used.

200 g of hot water at 80°C is added to 400 g of cold water at 10°C. Neglecting the heat taken by the container, calculate the final temperature of the mixture of water. Specific heat capacity of water = 4200 J kg^-1 K^-1.

1.0 kg of water is contained in a 1.25 kW kettle. Calculate the time taken for the temperature of water to rise from 25° C to it's boiling point 100° C. Specific heat capacity of water = 4.2 J g^-1 K^-1.

Heat energy is …………… during melting and it is …………… during freezing at a constant temperature.

1. rejected, absorbed
2. rejected, rejected
3. absorbed, absorbed
4. absorbed, rejected