Q.7.How do minerals occur in igneous and metamorphic rocks?
Ans.Minerals generally occur in these forms: In igneous and metamorphic rocks, minerals may occur in the cracks, crevices, faults and joints. The smaller occurrences are called veins and the larger one are called the Iodes. In most of the cases, they are formed when minerals in liquid/molten and gaseous forms are forced upwards through cavities towards the earth’s surface. They cool and solidify as they rise. Major metallic minerals like tin, copper, zinc and lead etc. are obtained from veins and lodes.
Q.8.How do minerals occur in sedimentary rocks?
Ans.
i). In sedimentary rocks, a number of minerals occur in beds or layers.Q.9. What are the uses of aluminum?
Ans.
i). It is used for making pots and pans because it a good conductor of heat.Q.10.Explain the formation of petroleum in India?
Ans.Most of the petroleum occurrence in India are associated with anticlines and fault traps in the rock formation of the Tertiary age. In regions of the folding, anticlines or domes, it occurs were oil is trapped in the crest of the unfold. The oil bearing layer is a porous limestone or sandstone through which oil may flow. The foil is prevented from rising or sinking by the intervening non-porous layers. Petroleum is also found in the fault traps between the porous and the non-porous rocks. Gas being lighter usually occurs above the oil.
Q.11Distinguish between magnetite and haematite.
Ans. Magnetite
i). It is the finest iron ore with a very high content of iron upto 70%.Q.12. What is gobar gas or biogas? State its three uses.
Ans.
i) It is an energy gas which is produced from the organic waste such as farm waste, shrubs, animals and human waste.Q.13.What are non-conventional sources or energy? Why there is a pressing need to use these resources of energy?
Ans.These are the sources of energy which are renewable.
i). The growing consumption of energy has resulted in the country becoming increasingly dependent on fossil fuels such as coal, oil and gas.Q.14.What is solar energy? What is its importance?
Ans. The energy obtained from the sun is called the solar energy.
i). Solar energy is free of cost.
ii). It does not cause any pollution.
iii). It is a non-conventional source of energy.
iv). It will reduce the dependence of rural households on firewood and dune cakes.