The  _________ minerals do not contain metals.

Which among the following is not a main mining center of coal ?

___________ play an important role in the development of human life.

On the basis of the type of the mineral and its commercial importance,minerals are classified into ______ groups.

In some oil fields, ________ is found along with mineral oil.

________ is required to make petrol .

The _________ minerals contain metal in raw form.

_____________ is the largest producer of bauxite in the world.

The __________ minerals are the most valuable minerals.

How many types of coal are there ?