CNG: Compressed Natural Gas.
LPG: Liquefied Petroleum Gas.

Natural gas is used as a starting material for the manufacture of a number of chemicals (petrochemicals) and fertilisers as it is a source of hydrogen gas needed to manufacture the fertilisers.

The slow process of conversion of dead vegetation into coal is called carbonisation.

Coke is tough, porous and black substance. It is almost pure form of carbon.

No, these will not be exhausted by human activities.

Coke

Exhaustible natural resources are as below: Coal, natural gas, petroleum, minerals, forests. Inexhaustible natural resources are as below: Air, sunlight, oxygen.

These resources are present in an unlimited quantity in nature and are not likely to be exhausted by human activities.

Petroleum is a natural resource, which was formed by the dead plants and animals in the sea. Their bodies sank to the bottom of the sea and were covered by several layers of sand and mud. Tremendous pressure and heat slowly converted the dead remains to petroleum and natural gas. The word Petroleum is derived from petra (rock) and oleum (oil) as it is mined from, between the rocks under earth. It is found trapped between sedimentary rock inside the earth under the land or under the sea. Petroleum, also called crude oil, is a mixture of hydrocarbons having different boiling points. The crude oil is split into various types of products like LPG, petrol, kerosene oil, diesel, lubricating oil, paraffin wax, asphalt, etc.

The natural resources which are present in a limited quantity in nature and can be exhausted (used up) by human activities are called exhaustible natural resources, e.g. coal, petroleum, natural gas, minerals, forests, wildlife, etc.
It requires millions of years for the conversion of the dead organisms into petroleum, from which petrol is separated. So, once the present stock of it gets exhausted, no new supplies of it will be available to us in the near future, whereas sunlight is present in an unlimited quantity in nature, so it is inexhaustible natural resource. It is not likely to be exhausted by human activities.

When coal is strongly heated in the absence of air in closed retorts, various useful products are obtained. These are coke, coaltar and coal gas.
Uses of coke Coke is used in the manufacture of steel and in the extraction of many metals. It acts as a fuel and it is a better fuel than coal.
Uses of coal tar The various compounds obtained from coal tar are used as starting materials for manufacturing a large number of substances used in everyday life and in industry like synthetic dyes, drugs, explosives, perfumes, plastics, paints, photographic materials, roofing materials, etc. Naphthalene balls used to repel moths and other insects are also obtained from coaltar.
Uses of coal gas It is used as a fuel in many industries situated near the coal processing plants.