Which of the following are conventional sources of energy ? A) Wood, dung cakes, coal and kerosene B) Diesel, electricity C) LPG, petrol, CNG D) All of them

There are two sources of energy: Conventional and Non - conventional. To attempt this question, we must know what are conventional sources of energy and what are non-conventional sources of energy. Complete answer: Conventional sources of energy are the natural energy resources which are present in a limited quantity and are being used for a long time. For example : oil, wood, LPG, CNG. Petrol, Coal etc. Non-conventional sources of energy are the energy sources which are continuously replenished by natural processes. These cannot be exhausted easily, can be generated constantly so can be used again and again, e.g. solar energy, wind energy, tidal energy, biomass energy and geothermal energy etc. These sources do not pollute the environment and do not require heavy expenditure. Non-conventional sources of energy are considered to be important as they are renewable, pollution-free, availability of them is in abundance, and they are environmentally friendly. For example : wave energy and tidal energy etc. Hence, option (d) is correct. Note: Always keep in mind that conventional source of energy are exactly same as non-renewable source of energy and non-conventional source of energy are also called renewable resources of energy as they can be replaced through natural processes at a rate equal to or greater than the rate at which they are consumed.