10 gm of ice at – 20°C is dropped into a calorimeter containing 10 gm of water at 10°C; the specific heat of water is twice that of ice. When equilibrium is reached, the calorimeter will contain

Heat given by water  Heat taken by ice to meltQ2 = 10 x 0.5 x [0 – (– 20)] + 10 x 80 = 900 calAs   so ice will not completely melt and final temperature = 0°C.As heat given by water in cooling up to 0°C is only just sufficient to increase the temperature of ice from – 20°C to 0°C, hence mixture in equilibrium will consist of 10 gm ice and 10 gm water at 0°C.