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7 questions · self-marked practice — reveal the answer and mark yourself.

Question 14 Marks
Write the names of five minerals and the useful substances obtained from them.
Answer
Some important minerals and ores are:
  1. Iron ore: It is used for making farming implements, rails of railway tracks etc.
  2. Manganese: Compounds of manganese are used in the preparation of medicines and for giving a pink tinge to glass. Manganese is also used in electrical appliances.
  3. Bauxite: It contains 55% Aluminium. Therefore, it is used mainly in aeroplanes, transport vehicles and to make electric wire.
  4. Copper: It is used to make electric wires as well as in radios, telephones, vehicles, and for making kitchen utensils and statues.
  5. Mica: Mica has many uses such as in ayurvedic medicines, dyes, electric machines and equipment, wireless communication equipment, etc.
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Question 24 Marks
Why is the diversity of plants and animals in the forests declining?
Answer
  1. The major causes of biodiversity decline are land use changes, pollution, changes in atmosphere, $CO_2$concentration, changes in the nitrogen cycle, acid rain, climate alteration and introduction of exotic species.
  2. All this is due to population growth.
  3. This is the main cause of the loss of biodiversity. More of wood for fuel is been used, more land is required for food production, livestock grazing etc.
  4. Rainforest land is converted to industrial and residential usage, so natural habitat of birds, animals is destroyed.
  5. Due to population growth most of wild land is converted to crop land. So no space for animals to live, their natural habitat is destroyed.
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Question 34 Marks
Why should we prevent the wastage of fuels used for vehicles?
Answer
  1. Vehicles are powered by gasoline or diesel petrol.
  2. Nowadays compressed natural gas (CNG) is also used.
  3. Aviation petrol, gasoline, diesel, we get from petroleum after fractional distillation.
  4. Petroleum is a non-renewable source of energy.
  5. It is getting depleted day by day and the demand for fuel has increased greatly due to the rapidly growing population.
  6. But the reserves of petroleum (fossil fuel) are limited.
  7. It is becoming difficult to meet the increased demand. So we should prevent the wastage of fuel.
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Question 44 Marks
What do we get from forest?
Answer
  1. A forest is a natural habitat of plants, animals and microbes. We get wood, firewood from trees like teak, mahogany, neem, subabhul.
  2. Also we get fibers, paper, rubber, gum and aromatic substances.
  3. We get many medicinal plants like Adulsa, Bel, Neem, Periwinkle, Cinnamon, Cinchona which are used for treatment of various diseases like cough, cold, diarrhea, fever, cancer, diarrhoea, nausea, malaria.
  4. We get fragrant essential oils from lemon grass, vanilla, kewada, khus, eucalyptus.
  5. In addition to this we get fruits, bulbs and roots, honey, sealing wax, catechu, dyes from forest.
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Question 54 Marks
What useful things will we have to do without if rubber is no longer available?
Answer
  1. Rubber has played a largely hidden role in global environment history for more than 150 years.
  2. In industries, rubber is needed to connect and protect all moving parts of machines.
  3. Native people used rubber for rubber boots.
  4. Household uses rubber in everything viz dish washing gloves, toys, jar seals, tyres in vehicles.
  5. Welcome mat at the door, Boots, raincoats, mattress cushions, earplugs, hot water bottles, surgical tubing and gloves, in labs, birth control device.
  6. In schools rubber bands, erasers, mouse pads, key board, rolling chair wheels. Head phone pads, rubber stamps are useful items used in schools and offices.
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Question 64 Marks
Observe the pictures and answer the question.

Image
1.What is the process shown in the given picture?
2.Explain the process.
3.What are the gaseous substances formed in the above process?
4.When the products of the process is refined, what other components are produced?

Answer
1.The process shown is formation of mineral oil and natural gas.
2.

  1. Mineral oil is the liquid fuel formed by the decomposition of organic substances buried underground.
  2. Millions of years ago, bodies of dead sea organisms sank to the bottom of the sea.
  3. Layers of soil and sand collected on them.
  4. Due to high pressure and temperature the remains of the dead organisms were transformed into mineral oil.
  5. The underground mineral oil is extracted through oil wells.


3.Natural gas is also formed along with mineral oil. It contains methane, ethane, propane and butane gases.
4.When mineral oil is refined by fractional distillation products produced are petrol, diesel, kerosene, naphtha lubricating oil, tar, etc.

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Question 74 Marks
What are the uses of forests?
OR
Write short note on forest and its uses.
Answer
  1. A forest is a natural habitat of plants, animals and microbes.
  2. Forest help improve and maintain the quality of environment.
  3. Forest helps in prevention of soil-erosion, help to control floods, protects wild life, maintains the balance of atmospheric gases.
  4. We get many medicinal plants from forest which help in treatment of various diseases.
  5. Examples Adulsa, Bel, Neem, periwinkle, amla tulsi, cinnamon.
  6. We also get wood, firewood from trees like teak, mahogani, neem, sababhul. Wood is useful for making furniture, farming implements, in construction work.
  7. Forest wealth includes fibres, paper, rubber, gum and aromatic substances.
  8. We get fragrant essential oils from lemon grass, vanilla, kewada and eucalyptus.
  9. They are used for making soaps, cosmetics and incense sticks. We get various fruits, bulbs, roots, honey, sealing wax, catechu dyes etc. from forest.
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