**Option 1**

- How much heat energy must be expended to heat water with a mass of 0.5 kg from 20 0C to 60 0C. The specific heat capacity of water is 4200 J / (kg – °C).
- What mass of ice at 0 0C must be placed in a glass of hot water at 50 0C for the ice to melt completely and the temperature of the water to become 0 0C? (Specific heat capacity of water is 4200 J/(kg – °C); Specific heat of melting of ice is 330 kJ/kg).
- How much energy does it take to heat ice weighing 800 grams and having an initial temperature of -10 ° C to 100 ° C and turn it into steam? (The specific heat of water is 4200 J/(kg – °C); the specific heat of ice is 2100 J/(kg – °C); the specific heat of melting of ice is 330 kJ/kg; the specific heat of vaporization of water is 2258 kJ/kg).
- How much alcohol must be burned to melt lead with a mass of 50 grams at 20 ° C? (the specific heat of combustion of alcohol is 26000 kJ; the specific heat of lead is 140 J/(kg – °Ñ); the specific heat of melting of lead is 22.6 kJ/kg).

**Option 2**

- How much heat will be released when water cools from 80 °C to 20 °C. The specific heat capacity of water is 4200 J/(kg – °C).
- How much mass of water at 50 0C must be poured into a glass with ice at 0 0C for the ice to melt completely and the temperature of the water to become 0 0C? (Specific heat capacity of water is 4200 J / (kg – °C); Specific heat of melting of ice is 330 kJ kg).
- How much energy does it take to heat ice weighing 200 grams and having an initial temperature of -5 °C to 100 °C and turn it into steam? (The specific heat of water is 4200 J/(kg – °C); the specific heat of ice is 2100 J/(kg – °C); the specific heat of melting of ice is 330 kJ/kg; the specific heat of vaporization of water is 2258 kJ/kg).
- How much firewood must be burned in order to heat 5 kg of water taken at 20°C up to boiling point? The heat loss is negligible. (The specific heat of combustion of wood is 10 MJ/kg; the specific heat of water is 4200 J/(kg – °Ñ)).

**Option 3**

- How much heat is needed to heat water from 10 ° C to 60 ° C. The specific heat capacity of water is 4200 J/(kg – °C).
- How many grams of ice at its melting point must be placed in a glass of hot water at 70 0C for the ice to melt completely and the temperature of the water to become 20 0C? (Specific heat capacity of water is 4200 J / (kg – °C); Specific heat of melting of ice is 330 kJ kg).
- How much energy does it take to heat ice with a mass of 600 grams and an initial temperature of -15 ° C to 100 ° C and turn it into steam? (The specific heat capacity of water is 4200 J/(kg – °C); the specific heat capacity of ice is 2100 J/(kg – °C); the specific heat of melting of ice is 330 kJ/kg; the specific heat of vaporization of water is 2258 kJ/kg).
- If we burn 20 kg of firewood, how much will 200 kg of water, taken at 20°C, be heated? Neglect the heat loss. (The specific heat of combustion of wood is 10 MJ/kg; the specific heat of water is 4200 J/(kg – °C)).

**Option 4**

- How much heat energy will be released when water cools by 30 °C. The specific heat capacity of water is 4200 J / (kg – °C).
- At 0 0C, how much mass of ice must be placed in a glass of hot water at 30 0C for the ice to melt completely and the water to become 10 0C? (Specific heat capacity of water is 4200 J / (kg – °C); Specific heat of melting of ice is 330 kJ kg).
- How much energy does it take to heat ice with a mass of 100 grams and an initial temperature of -8 ° C to 100 ° C and turn it into steam? (The specific heat capacity of water is 4200 J/(kg – °C); the specific heat capacity of ice is 2100 J/(kg – °C); the specific heat of melting of ice is 330 kJ kg; the specific heat of vaporization of water is 2258 kJ/kg).
- How much alcohol must be burned in order to melt lead with a mass of 40 grams, taken at 30 ° C? (the specific heat of combustion of alcohol is 26000 kJ; the specific heat of lead is 140 J/(kg – °C); the specific heat of melting of lead is 22.6 kJ/kg).