Spontaneous combustion of coal dust has resulted in many disastrous fires in coal mines.
What type of combustion is represented by :
(a) burning of white phosphorus in air at room temperature
(b) burning of LPG in a gas stove ?
(c) ignition of a cracker ?
(d) burning of coal dust in a coal mine ?
Fires in underground coal mines usually occur due to the :
(a) explosive combustion
(b) deliberate combustion
(c) spontaneous combustion
(d) rapid combustion
Geothermal energy is produced by the : (a) fission of radioactive materials (b) burning of coal inside the coal mines (c) combustion of natural gas deep inside the earth (d) fusion of radioactive substances