CBSE Class 10 Social Science Minerals and Energy Resources Important Questions Set 08

Answer: Placer deposits are minerals that occur in alluvial sands of valley floors and the base of hills. Gold, silver, tin and platinum are examples.

Teacher's Note:
1. They are formed by the deposition of eroded material.
2. They do not need mining of veins or lodes.

Answer: It is a method of mining in the tribal areas of north-east India where individuals or communities dig long narrow tunnels to extract minerals, often illegally.

Teacher's Note:
1. It is widely practised in Meghalaya for coal.
2. Such mining is dangerous and poorly regulated.

Answer: Magnetite, with an iron content of over 70 per cent, is the finest iron ore. It has excellent magnetic qualities.

Teacher's Note:
1. It is valuable in the electrical industry.
2. Hematite is slightly lower, with 50 to 60 per cent iron.

Answer: Odisha is the largest bauxite-producing state in India, with Panchpatmali deposits in Koraput district. Aluminium is extracted from bauxite.

Teacher's Note:
1. Bauxite is the chief ore of aluminium.
2. Aluminium is a light metal with good conductivity.

Answer: Anthracite is the highest quality hard coal, with more than 80 per cent carbon. It is hard and burns with little smoke.

Teacher's Note:
1. Lignite has the lowest carbon content among these.
2. Remember the order: lignite, bituminous, anthracite.

Answer: The Puga valley is in Ladakh. Another experimental geothermal project is in the Parvati valley near Manikaran in Himachal Pradesh.

Teacher's Note:
1. Both are experimental in nature.
2. Geothermal energy is heat from inside the Earth.

Answer: 1. Mica is used in electric and electronic industries because of its insulating properties.
2. Major deposits lie in Gaya-Hazaribagh in Jharkhand and Ajmer in Rajasthan, and also Nellore in Andhra Pradesh.

Teacher's Note:
1. Mica can be split into very thin sheets.
2. Give two uses and two regions.

Answer: 1. Lignite is low grade brown coal, soft with high moisture content, found at Neyveli in Tamil Nadu.
2. Bituminous coal is the most popular for commercial use and has a carbon content of 60 to 80 per cent.
3. Anthracite is the best quality, with more than 80 per cent carbon.

Teacher's Note:
1. Coal quality depends on the carbon content.
2. State the feature of each type separately.

Answer: Geothermal energy is the heat and electricity produced using the heat from the interior of the Earth. The projects are in the Parvati valley near Manikaran in Himachal Pradesh and the Puga valley in Ladakh.

Teacher's Note:
1. It is clean and renewable in nature.
2. Name both places correctly.

Answer: 1. The work is risky, and poisonous fumes cause pulmonary diseases in miners.
2. Roofs of mines can collapse and coal mines can catch fire.
3. Water sources are contaminated by mining waste.

Teacher's Note:
1. Mining also degrades land.
2. Link each reason with health or safety.

Answer: 1. Coal and petroleum are exhaustible resources.
2. India has abundant deposits of uranium and thorium.
3. It is useful in medicine and agriculture, and hydel power has environmental limitations.

Teacher's Note:
1. Safety and waste disposal remain concerns.
2. Name uranium and thorium.

Answer: 1. Rajasthan is a hot and dry region with clear skies for most of the year.
2. Installation of plants is cheaper in such areas.
3. Solar energy is renewable and pollution free, and government support is available.

Teacher's Note:
1. India lies in the tropics and receives plenty of sunshine.
2. Link climate with solar potential.

Answer: 1. Use public transport instead of individual vehicles.
2. Switch off electrical devices when not in use and use power saving devices.
3. Use non-conventional sources, which are renewable and eco-friendly.
4. Intensify research on new sources.

Teacher's Note:
1. Saving energy is as important as finding new sources.
2. Practical actions earn marks.

Answer: 1. Veins and lodes: minerals occur in cracks, crevices, faults or joints, such as tin, copper, zinc and lead.
2. Beds or layers: occur in sedimentary rocks, such as coal and iron ore.
3. Placer deposits: found in alluvial sands, such as gold and silver.
4. Ocean waters: such as common salt, magnesium and bromine.
5. Residual mass of weathered material, such as bauxite.

Teacher's Note:
1. The mode of occurrence decides the mining method.
2. Match each mode with an example mineral.

Answer: 1. Odisha-Jharkhand belt: Mayurbhanj and Keonjhar in Odisha, Singhbhum in Jharkhand.
2. Durg-Bastar-Chandrapur belt in Chhattisgarh and Maharashtra, including Bailadila.
3. Bellary-Chitradurga-Chikkamagaluru-Tumakuru belt in Karnataka, including Kudremukh.
4. Maharashtra-Goa belt.
5. India has abundant iron ore, mainly magnetite and hematite.

Teacher's Note:
1. Much ore is exported through ports like Paradip.
2. Name the belts and one state each.

Answer: 1. Conventional sources are generally exhaustible, for example coal, petroleum, natural gas and electricity.
2. Non-conventional sources are renewable, for example solar, wind, tidal, geothermal and biogas.
3. Conventional sources cause pollution, while non-conventional sources are mostly clean.
4. Conventional sources are widely used now, while non-conventional ones need more investment.
5. India is increasing the use of non-conventional sources.

Teacher's Note:
1. The aim is to move towards sustainable energy.
2. Use examples for each type.

Answer: 1. Minerals are finite, non-renewable resources that take millions of years to form.
2. Rich deposits are small in volume compared with low-grade ores.
3. Continuous extraction raises costs as mining goes deeper.
4. Recycling metals, using scrap and using substitutes help conserve them.
5. Conservation protects the needs of future generations.

Teacher's Note:
1. Mining also damages the environment.
2. Suggest at least two ways to conserve.