question_answer 15)

  Compressed Natural Gas (CNG) is (a) propane                        (b) methane                      (c) ethane                           (d) butane

Answer:

                  (b) Compressed Natural Gas (CNG) is the best and cheap fuel. It has replaced petrol and diesel fuel as it is considered as clean fuel. CNG consists of around 90% methane, by compressing it to less than 1% of volume it occupies at standard atmospheric pressure. Propane and butane together form LPG or liquified petroleum gas while ethane is used in chemical industry to produce ethene.