CNG and LPG burn more cleanly than petrol, diesel, coal or wood. They produce less smoke and harmful gases, are easy to transport and handle, and have good heat output.
Bitumen.
Millions of years ago, dense forests were buried under soil and sediments. Under high pressure and temperature, dead plants slowly changed into coal. This slow conversion of dead vegetation into coal is called carbonisation.
Coal, petroleum and natural gas; refining; CNG.
(a) False (b) False (c) True (d) True (e) False.
They are present in limited quantities and take millions of years to form. Human use is much faster than their formation, so they can be exhausted.
Coke is a tough, porous, black substance and is almost pure carbon. It is used in manufacturing steel and in extraction of many metals.
Petroleum formed from dead sea organisms buried under sand and clay. Over millions of years, absence of air, high pressure and high temperature converted the remains into petroleum and natural gas.
Draw a line graph with year on the x-axis and shortage percentage on the y-axis. Plot the points (1991, 7.9), (1992, 7.8), (1993, 8.3), (1994, 7.4), (1995, 7.1), (1996, 9.2), (1997, 11.5) and join them.