Explain various harmful effects of burning fuels.
Fuels are very useful for us. But there are certain disadvantages of burning fuels.
(i) Fuels like wood, coal, petroleum, etc. which are carbon fuels generally release unburnt carbon particles which are quite harmful. They cause various respiratory and skin diseases.
(ii) In most of the cases carbon dioxide is released during burning of fuels. This carbon dioxide is released in environment. This carbon increases the temperature of the earth, which is called global warming.
(iii) Incomplete combustion of fuels release many poisonous gases like carbon monoxide in the environment. These poisonous gases create air pollution, such air if inhaled can be fatal.
(iv) Combustion of coal and diesel generates sulphur dioxide. It is a corrosive gas and it causes suffocation.
(v) Burning of petrol releases nitrogen oxides. These oxides of nitrogen and sulphur dioxide combine with rain water to cause acid rain. it affect aquatic life and natural environment.
Fuel must be heated to its __________ before it starts burning.
List conditions under which combustion can take place.
Conditions necessary for combustion are :
(i) Presence of combustible substance.
(ii) Attainment of ignition temperature.
(iii) Proper supply of air to provide oxygen.
Burning of wood and coal causes __________ of air.
Fire produced by oil cannot be controlled by ___________ .
A liquid fuel, used in homes is __________