(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 coaltar.
(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 __________.
Ans. (a) carbonization,
(b) fossil fuels,
(c) unpleasant,
(d) coal gas,
(e) refining,
(f) air pollution
