The greenhouse effect is due to an excessive emission of

• oxides of sulphur

• oxides of nitrogen

• carbon dioxide

• oxides of carbon

What are the advantages of using CNG and LPG as fuels?

Name the petroleum product used for surfacing of roads.

Describe how coal is formed from dead vegetation. What is this process called?

Fossil fuels are ________, ________ and ________.

Process of separation of different constituents from petroleum is called __________.

Least polluting fuel for vehicle is ________.

Fossil fuels can be made in the laboratory.

CNG is more polluting fuel than petrol.

Coke is almost pure form of carbon.

Coal-tar is a mixture of various substances.