1. Multiple choice questions.
(i) Which one of the following minerals is formed by decomposition of rocks, leaving a residual mass of weathered material?
(ii) Koderma, in Jharkhand is the leading producer of which one of the following minerals?
(c) iron ore
(iii) Minerals are deposited and accumulated in the stratas of which of the following rocks?
(a) sedimentary rocks
(b) metamorphic rocks
(c) igneous rocks
(d) none of the above
(iv) Which one of the following minerals is contained in the Monazite sand?
2. Answer the following questions in about 30 words.
(i) Distinguish between the following in not more than 30 words.
(a) ferrous and non-ferrous minerals
Ans. Metallic minerals which contain iron are called ferrous minerals, e.g. iron ore, manganese, nickel, cobalt, etc. On the other hand, non-metallic minerals which do not contain iron are called non-ferrous minerals, e.g. copper, bauxite, tin, etc.
(b) conventional and non-conventional sources of energy
Ans. Sources of energy which have been in use since a long time are called conventional sources of energy, e.g. coal, firewood, petroleum, hydel energy, etc. Sources of energy which have come into use recently are called non-conventional sources of energy, e.g. solar energy, wind energy, nuclear energy, etc.
(ii) What is a mineral?
Ans. A homogeneous, naturally occurring substance with definable internal structure is called mineral.
(iii) How are minerals formed in igneous and metamorphic rocks?
Ans. In igneous and metamorphic rocks, the smaller occurrences are called veins and the larger occurrences are called lodes. They are usually formed when minerals in liquid/molten and gaseous forms are forced upwards through cavities towards the earth’s surface. Examples: tin, copper, zinc, lead, etc.
(iv) Why do we need to conserve mineral resources ?
Ans. It takes millions of years for the formation of minerals. Compared to the present rate of consumption, the replenishment rate of minerals is very slow. Hence, mineral resources are finite and non-renewable. Due to this, it is important that we conserve the mineral resources.
3. Answer the following questions in about 120 words.
(i) Describe the distribution of coal in India.
Ans. In India, coal occurs in rock series of two main geological ages. The Gondwana coal was formed over 200 million years ago. The tertiary deposits are about 55 million years old. The major sources of Gondwana coal are located in the Damodar valley (West Bengal-Jharkhan). In this belt, Jharia, Raniganj and Bokaro are important coalfields. Coal deposits are also present in the Godavari, Mahanadi, Son and Wardha valleys. Tertiary coal is found in the north-eastern states of Meghalaya, Assam, Arunachal Pradesh and Nagaland.
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(ii) Why do you think that solar energy has a bright future in India?
Ans. India is a tropical country. It has enormous possibilities of tapping solar energy. Photo-voltaic technology converts sunlight directly into electricity Solar energy holds great promises for the future. It can help in minimizing the dependence on firewood and animal dung cakes in rural areas. This will also help in conservation of fossil fuels.