question_answer 28)

  Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her to identify the correct set of conditions. (a) Low temperature, low pressure                         (b) High temperature, low pressure (c) Low temperature, high pressure                        (d) High temperature, high pressure

Answer:

  (c) Low temperature and high pressure are required to liquefy gases to liquids. There is a lot of space between the particles of a gas. On applying high pressure, the particles of gas move get so close that they start attracting each other sufficiently forming a liquid. When gas is compressed too much, heat is produced, so it is necessary to cool it. Cooling lowers the temperature of compressed gas and helps in liquefying it, Hence, a gas can be liquefied by applying high pressure and lowering the temperature (cooling).