Coal and petroleum are the fossil fuels, which take lots of years to form. They are being used continuously but the formation rate is very low in comparison to that of consumption. That is why they are known as exhaustible natural resources. 

 There are a large number of natural resources of air, water and sunlight. These will not get exhausted in spite of continuous usage. Forests, if continuously cut down will get exhausted. They are renewable but an exhaustible resource. 

 Renewable resources are the ones, which can be replenished at a rate at, which they are consumed. Air, water, and sunlight are present in huge amounts in nature but formation of petroleum takes millions of years and cannot be replenished at the rate at, which it is consumed. 

Decomposition of dead plants and animals for the formation of coal and petroleum requires very high temperature and high pressure. This is because the high temperature and pressure maximise the activity of microorganisms. 

 Non-renewable resources are the ones, which can not be replenished at the rate at which they are consumed. Also, they can't be recycled to optimize their usage. This applies to minerals and fossil fuels and so, they are known as non renewable resources. 

Coal is widely used to generate energy in thermal power stations, railway engines, and industries but is not used as a fuel in the vehicles.

 Coal is formed from the decomposition of dead organic matter, which is mainly composed of carbon. That is why the major constituent of coal is also carbon. 

Fossil fuels are the fuels, which are formed due to the decay of dead plants and animal remains. This process takes millions of years. Coal and petroleum are formed in nature with the same process. So, they are known as fossil fuels. 

Carbonisation is the process of gradual conversion of the remains of dead plants and animals into coal.

Complete combustion of the fuel takes place when heated in sufficient supply of air. Combustion of carbon based fuel results in the release of carbon dioxide along with large amount of heat energy.

Processing of coal leads to the formation of many useful substances like coke, coal gas, coal tar etc. Natural gas is formed from the processing of petroleum and not from coal.

Decomposition takes place deep under the surface of the earth due to the activity of anaerobic bacteria/microorganisms. Absence of oxygen is a pre-requisite for this.

Carbonization is the process of gradual conversion of remains of dead plants and animals into coal. Coke, coal tar and coal gas are the useful substances obtained by further processing of coal.

Naphthalene is a useful product obtained by the processing of coal tar, which itself is obtained by the processing of coal.

 Bitumen is the thick, sticky substance, which is obtained by the processing of petroleum and is used for paving roads. 

 Biogas is produced by the biological breakdown of organic matter in absence of oxygen. Natural gas is basically methane. It is formed in a natural way or obtained during the formation of petroleum oil. Coal gas is the gas, which is obtained as the by product during processing of coal to get coke. 

Diesel, petrol and kerosene oil are the products obtained during the processing of crude oil petroleum. Coke is the by-product obtained during processing of coal.

Coal tar is a liquid substance with thick composition. It is black in colour and has got an unpleasant smell.

 Coal is a fossil fuel, which has been a source of energy for a long time. It was also used earlier to run steam engines. 

Coal gas produces a large amount of energy and is generally supplied through pipes. As a result of this property, it was first used for street lighting in London.

Petrol is comparatively costlier than the other fuels. Kerosene oil is inflammable and easily catches fire. Lubricating oil is used to lubricate the engine of automobiles. Diesel is cheaper and produces large amount of energy to run heavy vehicles.

Petrol and coal tar are the products obtained by the processing of petroleum and coal, respectively. Coal is formed deep under the surface of earth due to the decay and decomposition of dead plants and animals. Petroleum is formed deep under the sea due to the decay and decomposition of sea plants and sea animals.

Lubricating oil, petrol and diesel are the products, which are obtained by the processing of petroleum. Petroleum is the crude oil obtained by decomposition of organic matter and has foul smell. 

Coal tar is obtained from the processing of coal. It can easily take up variety of colours. It is a thick viscous substance and thus, is useful for making paints, dyes, etc. 

Natural gas accumulates above the surface of petroleum oil during its formation. Methane is formed in a natural way or obtained during the formation of petroleum oil. Biogas is produced by biological breakdown of organic matter in the absence of oxygen. Coal gas is obtained as a by-product during the processing of coal so as to obtain coke.