Coal and Petroleum

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 __________.