If coal gives off 7000 kcal/ kg when it is burnt, how much coal will be needed to heat a house that requires `4.2xx10^(7)` kcal for the whole winter? Assume that an additional 30 percent of the heat is lost up the chimney.

A vessel made of copper weighs 1 kg and it contains 1 kg of water at 10^(@)C . How much coal will be required to raise the temperature of this water to 100^(@)C ? On burning 1 kg of coal, 10^(4) cal of heat can be produced and 40% of this heat is lost. Specific heat of copper ="0.09 cal.g"^(-1).^(@)C^(-1) .

5.00 kg of liquid water is heated to 100. 0^@ C in a closed system At this temperature , the density of liquid water is 958 kg/ m^3 . The pressure is maintained at atmospheric pressure of 1.01 xx 10^5 Pa. A moveable piston of negligible weight rests on the surface of the water. The water is then converted to steam by adding an additional amount of heat to the system. When all of the water is converted, the final volume of the steam is 8.50 m^3 . The latent heat of vaporization of water is 2.26 xx 10^6 J/kg. How much heat is added to the system in the isothermal process of converting all of the water into steam?

The mass of a copper steam boiler is 200 kg. It contains 100 kg of water at 25^(@)C.7xx10^(6) cal of heat is produced by burning 1 kg of coal and only 3% of it is absorbed by the boiler to heat water. How much coal is to be burnt to raise the temperature of the water in the boiler to its boiling point? Specific heat of copper ="0.09 cal.g"^(-1).^(@)C^(-1) .

During exercise, a person may give offf 180 kcal of heat in 30 min by evaporation of water from the skin. How much water has been lost? Given that latent heat of vaporization of water is 540 cal/gm.

A sample of air weighing 1.18 g occupies 1.0 xx 10^(3) cm^(3) when kept at 300 K and 1.0 xx 10^(5) pa. When 2.0 cal of heat is added to it constant volume, its temperature increases by 1^@C . Calculate the amount if heat needed to increases the temperature of air by 1^@C at constant pressure if the mechanical equivalent of heat si 4.2 xx 10^(-1) . Assume that air behaves as an ideal gas.

A sample of air weighing 1.18 g occupies 1.0 xx 10^(3) cm^(3) when kept at 300 K and 1.0 xx 10^(5) pa. When 2.0 cal of heat is added to it constant volume, its temperature increases by 1^@C . Calculate the amount if heat needed to increases the temperature of air by 1^@C at constant pressure if the mechanical equivalent of heat si 4.2 xx 10^(-1) . Assume that air behaves as an ideal gas.

A sample of air weighing 1.18 g occupies 1.0 xx 10^(3) cm^(3) when kept at 300 K and 1.0 xx 10^(5) pa. When 2.0 cal of heat is added to it constant volume, its temperature increases by 1^@C . Calculate the amount if heat needed to increases the temperature of air by 1^@C at constant pressure if the mechanical equivalent of heat si 4.2 xx 10^(-1) . Assume that air behaves as an ideal gas.