Q What are the different forms in which minerals occur in nature?

Ans. Minerals generally occur in nature in the following forms :

  • 1. In igneous and metamorphic rocks : Minerals may occur in cracks, crevices, faults or joints in igneous and metamorphic rocks. The smaller occurrences are called ‘veins’ and the larger occurrences are called ‘lodes’. In most 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, etc., are obtained from veins and lodes.
  • 2. In sedimentary rocks : In sedimentary rocks, a number of minerals occur in beds or layers. They have been formed as a result of deposition, accumulation and concentration in horizontal strata. Coal and crude oil have been concentrated as a result of million years under great heat and pressure.
  • 3. In decomposed rocks :Another mode of formation involves the decomposition of surface rocks and the removal of soluble constituents, leaving a residual mass of weathered material.
  • 4. Minerals in alluvial deposits : Certain minerals may occur as alluvial deposits in sands of valley floors and the base of hills. These deposits are called ‘placer deposits’. Gold, silver, tin and platinum are among such minerals.
  • 5. Minerals in ocean water : The ocean water contains vast quantities of minerals, but most of these are too widely diffused to be of economic significance. Common salt, magnesium and bromine are largely derived from ocean water.

Q Name some river valley projects and write the names of the dams built on these rivers.

Ans. River valley projects Dams

  • 1. Bhakra Nangal project on river Sutlej
  • 2. Chambal valley project
  • 3. Mahanadi river project
  • 4. Rihand project on river Son
  • 5. Krishna river project
  • 6. Farakka project on river Ganga
  • 7. Tungabhadra river project
  • 1. Bhakra Nangal Dam
  • 2. Gandhi Sagar, Ratna Pratap Sagar, Jawahar Sagar
  • 3. Hirakud
  • 4. Rihand
  • 5. Nagarjuna Sagar
  • 6. Farakka
  • 7. Tungabhadra

Q Fill the names of the correct minerals in the crossword given below :

40
  • Across
  • 1. A ferrous mineral (9).
  • 2. Raw material for cement industry (9).
  • 3. Finest iron ore with magnetic properties (9).
  • 4. Highest quality hard coal (10).
  • 5. Aluminium is obtained from this ore (7).
  • 6. Khetri mines are famous for this mineral (6).
  • 7. Formed due to evaporation (6).
  • Down
  • 1. Found in placer deposit (4).
  • 2. Iron ore mined in Bailadila (8).
  • 3. Indispensable for electrical industry (4).
  • 4. Geological age of coal found in northeast India (8).
  • 5. Formed in veins and lodes (3).
  • (i) Minimising use of water for processing by reusing and recycling it in two or more successive stages.
  • (ii) Harvesting of rainwater to meet increasing water requirements.
  • (iii) Treating hot water and effluents before releasing them into rivers and ponds. Treatment of industrial effluents can be done in three phases :
  • (a) Primary treatment by mechanical means. This involves screening, grinding, flocculation and sedimentation.
  • (b) Secondary treatment by biological process.
  • (c) Tertiary treatment by biological, chemical and physical processes.
  • (iv) Overdrawing of groundwater reserves by industries where there is a threat to groundwater resources also needs to be regulated legally.
Ans. Across : 1. Manganese, 2. Limestone, 3. Magnetite, 4. Anthracite, 5. Bauxite, 6. Copper, 7. Gypsum.
Down : 1. Gold, 2. Hematite, 3. Mica, 4. Tertiary, 5. Tin.

Q A factory produces aluminium saucepans with plastic handles. It obtains aluminium from a smelter and a plastic component from another factory. All the manufactured saucepans are sent to a warehouse :

  • (i) (a) Which raw material is likely to be most expensive to transport and why ?
  • (b) Which raw material is likely to be the cheapest to transport and why ?
  • (ii) Do you think the cost of transporting the finished products after packaging is likely to be cheaper or more expensive than the cost of transporting aluminium and plastic? Why ?
  • Ans. (i) (a) Aluminum is supposed to be an expensive raw material because it is heavier than plastic, and also the saucepan body is bulkier than the handle.
  • (b) Plastic is cheaper because it is lighter than aluminium.
  • (ii) Cost of transporting finished products after packaging will be cheaper because they are likely to be enclosed in rectangular packing boxes, which can be easily transported in larger quantities by proper stacking, either by goods train or by truck.

Q Select one agro-based and one mineral-based industry in your area.

  • (i) What are the raw materials they use?
  • (ii) What are the other inputs in the process of manufacturing that involve transportation cost?
  • (iii) Are these factories following environmental norms?

Ans. One agro-based industry located in my area is the vegetable oil industry. They use sunflower seeds to extract oil. They follow the environment norms by using environment-friendly equipments and send the waste products for recycling.

One mineral-based industry located in my area is the heavy machinery industry. They use iron which they get from the nearby iron ore factory. They follow eco-friendly techniques for manufacturing and dispose the waste in a suitable manner. They do not dump the waste in the nearby river; instead they send it for recycling.