4. As per Charles' law, the volume of a given mass of a perfect gas varies __________ as its absolute temperature, when the absolute pressure remains constant.
Correct Answer: It is impossible to transfer heat from a body at a lower temperature to a body at a higher temperature, without the aid of an external source.
10. The amount of heat obtained by the complete combustion of 1 kg of a fuel when the products of its combustion are cooled down to the temperature of supplied air is called __________ calorific value offuel.