161) The absolute pressure of a given mass of a perfect gas varies inversely as its volume, when the temperature remains constant. This statement is known as Boyle's law.

162) The fuel mostly used in cement industry and in metallurgical processes is

163) Boyle's law states that change of internal energy of a perfect gas is directly proportional to the change of temperature.

164) The ratio of specific heat at constant pressure (c_p) and specific heat at constant volume (c_v) is always __________ one.

165) The isothermal and adiabatic processes are regarded as