Fill in the blanks.

(a) The slow process of conversion of dead vegetation into coal is called__________.


(b) Coal and petroleum are formed from the dead remains of organisms and are known as __________.


(c) The black thick liquid with __________ smell is known as coal tar.


(d) During the processing of coal to get coke, coal tar and__________ are also obtained.


(e) The process of separating the various constituents of petroleum is known as __________.


(f) Excessive burning of fossil fuels is a major cause of __________.


a) Carbonization


Carbonization is the process of slow conversion of dead plants into coal under high pressure, temperature and in absence of air.


b) Fossil fuels


Coal and petroleum are known as fossil fuels as they are obtained from dead remains of plants and animals.


c) Unpleasant


Coal tar is a product of coal which is a thick black liquid with unpleasant smell used for road surfacing.


d) Coal gas


Coal gas is a product of coal which is a gaseous fuel obtained during processing of coal to get coke.


e) Refining


Refining is the process of separating various components of petroleum in a refinery and this method employs fractional distillation technique.


f) Air pollution


Fossil fuels mainly contain carbon and burning of these fuels release carbon dioxide gas which causes air pollution.


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