Fill in the blanks :
(a) ______________is formed when wood is burnt in a limited supply of air.
(b) Coal is a _______________ form of carbon.
(c) __________________ is the most inferior form of coal.
(d) Wood charcoal is a _______________conductor of heat and electricity.
(e) __________________is used in making black shoe polish
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 __________.