Natural Resources | Class 7 | Science | Chapter 16 | Maharashtra State Board
Explore the fascinating world of natural resources in our lessons. Learn how minerals, including iron ore, manganese, bauxite, copper, and mica, are formed and classified. Dive into the realm of fuels like coal, mineral oil, and natural gas. Discover the importance of conserving forests and unlocking mineral and bio-resources from the ocean. Join us on a journey to understand, appreciate, and sustainably manage Earth’s wealth.
Questions & Answers
1. Describe natural resources with reference to the following three types.
(a) Mineral resources (b) Forest resources (c) Ocean resources
Ans. (a) Mineral Resources:
Definition: Mineral resources are naturally occurring substances found in the Earth’s crust. They are usually solid, inorganic, and have a crystal structure.
Types:
Metallic Minerals: These minerals contain metals and exhibit characteristics like luster or shine. Examples include silver, copper, iron, gold, and zinc.
Non-metallic Minerals: These minerals do not contain extractable metals. Examples include dimension stone, halite (salt), sand, gypsum, and gravel.
Uses: Minerals are essential for various industries. Aluminium, for instance, is used in aircraft, shipping, and car manufacturing. Gold and silver find applications in jewellery, while copper is vital for coins and pipes.
(b) Forest Resources:
Definition: Forest resources refer to biotic and abiotic elements found in forests. They satisfy human needs and play a crucial role in ecosystems.
Types:
Timber Forest Resources: These include wood and other forest products used for construction, furniture, and paper.
Non-timber Forest Resources: These are products other than wood, such as medicinal plants, food (fruits, roots), and industrial materials.
Examples: Forests provide food, fuel, medicines, and building materials. They also contribute to climate regulation and oxygen production.
(c) Ocean Resources:
Definition: Ocean resources are derived from saltwater bodies. They include both biotic and abiotic elements.
Types:
Biotic Resources: Living organisms in the ocean, such as fish, plankton, and marine mammals.
Abiotic Resources: Non-living elements, including minerals, energy (like oil and gas), and oxygen production.
Importance: Oceans support economies, provide jobs, and influence climate. They are essential for life on Earth.
2. Write answers to the following questions in your own words.
(a) What is meant by fossil fuel? What are their types?
Ans. Fossil fuels are natural energy sources formed from the remains of ancient plants and animals buried and subjected to heat and pressure over millions of years. The three main types of fossil fuels are:
1. Coal: Formed from the remains of plants in swampy environments.
2. Oil (Petroleum): Derived from the decay of marine organisms in ancient oceans.
3. Natural Gas: Formed from the same organic materials as oil, but under conditions that result in the formation of gas.
(b) Make a list of the components we obtain from mineral oil.
Ans. Components obtained from mineral oil include:
1. Petrol (Gasoline): Used as fuel for vehicles.
2. Diesel: Commonly used as fuel for trucks, buses, and some cars.
3. Jet Fuel: Used for aviation.
4. Lubricating Oils: Used to reduce friction in machinery.
5. Bitumen: Used in road construction.
6. Paraffin Wax: Used in candles, cosmetics, and polishes.
7. Petrochemicals: Used in the production of plastics, synthetic fibers, and various chemicals.
(c) What do we get from forests?
Ans. From forests, we get:
1. Timber: Wood for construction and furniture.
2. Paper: Derived from wood pulp.
3. Medicinal Plants: Sources of traditional and modern medicines.
4. Oxygen: Trees release oxygen during photosynthesis.
5. Biodiversity: Habitat for various plant and animal species.
6. Recreation: Places for outdoor activities and tourism.
(d) What are the items included in ocean resources? What are their uses?
Ans. Ocean resources include:
1. Fisheries: Provide food and livelihoods.
2. Oil and Gas: Extracted for energy production.
3. Minerals: Used in various industries.
4. Salt: Harvested for consumption and industry.
5. Renewable Energy: Generated through tidal and wave power.
6. Biodiversity: Supports diverse marine ecosystems.
7. Transportation Routes: Facilitate global trade and shipping.
(e) Why should we prevent the wastage of fuel used for vehicles?
Ans. Preventing the wastage of fuel for vehicles is essential because it conserves resources, reduces air pollution, and helps mitigate the impact of climate change. Additionally, it saves money for individuals and promotes energy sustainability for future generations.
(f) Why is the diversity of plants and animals in the forests declining?
Ans. The diversity of plants and animals in forests is declining primarily due to habitat loss caused by deforestation, human encroachment, and unsustainable logging. Additionally, factors like climate change, pollution, and invasive species contribute to the decline in biodiversity.
(g) Write the names of five minerals and the useful substances obtained from them.
Ans.
1. Iron Ore: Obtains iron, used in the production of steel.
2. Bauxite: Yields aluminium, used in construction and transportation.
3. Copper Ore: Extracts copper, essential for electrical wiring and technology.
4. Coal: Produces energy and is a key ingredient in steel production.
5. Gold Ore: Yields gold, used in jewellery, electronics, and as an investment.
(h) Name the two important stages in the process of obtaining metals from ores?
Ans. The two important stages in the process of obtaining metals from ores are:
1. Mining: The extraction of ores from the Earth's crust.
2. Metallurgy: The process of extracting and refining metals from their ores through various physical and chemical methods.
3. What steps are taken for protection and conservation of natural resources?
Ans. Protecting and conserving natural resources is important to ensure a healthy environment for both people and wildlife. Here are some simple steps taken for their protection:
1. Reduce, Reuse, Recycle: Minimize waste by using items wisely and recycling materials.
2. Save Water: Conserve water by fixing leaks and using it efficiently.
3. Energy Efficiency: Use energy-efficient appliances and bulbs to reduce energy consumption.
4. Plant Trees: Support tree planting for a healthier environment.
5. Wildlife Protection: Preserve natural habitats to safeguard biodiversity.
6. Spread Awareness: Educate others about the importance of protecting natural resources.
7. Sustainable Practices: Support eco-friendly businesses and practices.
8. Government Regulations: Follow and advocate for environmental laws.
9. Conserve Energy: Turn off lights and electronics when not in use.
10. Responsible Fishing/Farming: Practice sustainable methods to avoid resource depletion.
By taking these steps, we can all contribute to the protection and conservation of natural resources, ensuring a healthier planet for current and future generations.
4. Complete the flow chart.
5. How does the economic condition of a nation depend on its natural resources?
Ans. The economic condition of a nation depends on its natural resources because these resources, like minerals, forests, and water, contribute to industries, agriculture, and energy production. Nations with abundant and well-managed natural resources often have stronger economies as they can meet domestic needs, export goods, and attract investments, driving economic growth. Conversely, poor management or depletion of natural resources can lead to economic challenges.
6. Which medicinal plants will you grow on your school premises and near your house? Why?
Ans. I would consider growing medicinal plants like aloe Vera, mint, and tulsi (holy basil) on my school premises and near my house. Aloe Vera has healing properties for skin issues, mint aids digestion, and tulsi is known for its medicinal and immune-boosting qualities. These plants provide natural remedies, promoting health and well-being for both students and family members.
E X T R A
1. Fill in the blanks:
1. Cow dung is the major raw material for biogas.
2. Atomic energy is obtained by using ores of Uranium.
3. Biogas generation is mainly based on the principle of Fermentation.
4. Floods can be prevented by Afforestation.
5. Coal, petroleum, natural gas are non-renewable resources.
6. The total percent of land of world under forest cover is 30%.
7. A naturally occurring substance minerals.
8. Minerals that contain a high proportion of metal are called ore.
9. Coal, mineral oil and natural gas are fossil fuel.
10. Deposits of common salt are also found in the earth. This salt is called rock salt.
11. Mineral oil is the liquid fuel formed by the decomposition of organic substances.
12. The underground mineral oil is extracted through oil wells.
13. Mineral oil is also known as petroleum or crude oil.
14. Fossil are the preserved remains of dead organisms in rock.
15. Coal can be formed from Fossils.
16. Impurities of sand and soil in ore are called Gangue.
17. Coal mainly contains carbon.
18. Petroleum is formed from organisms in sea.
19. Separation of various fractions of petroleum is called Refining.
20. We can obtain minerals from rocks by mining.
21. Bauxite is the most important ore of aluminium.
22. Anthracite is the coal of the highest grade.
23. Metals are obtained from their ore by extraction and purification.
24. ONGC is the largest oil and gas research and production company in India.
25. Natural gas is transformed under high pressure into LNG and CNG.
26. The main component of Natural gas is Methane.
27. Sandalwood and oil of Eucalyptus are used for adding fragrance in soaps and incense sticks.
28. Adulsa is a natural herbal medicine for cough and cold.
2. Answer the following:
1. What is meant by natural resources?
Ans. Natural resources are substances and materials found in the environment that are essential for human survival and contribute to economic activities. Examples include air, water, soil, minerals, forests, and wildlife.
2. What are alternative fuels?
Ans. Alternative fuels are substitutes for traditional fossil fuels, such as biofuels, hydrogen, natural gas, and electricity, aimed at reducing environmental impact and promoting sustainability.
3. What is meant by fuels?
Ans. Fuels are substances that release energy when burned or processed, providing power for various applications such as transportation, heating, and electricity generation. Examples include gasoline, diesel, natural gas, and coal.
4. Which natural resources do we use as fuels?
Ans. We use various natural resources as fuels, including:
1. Fossil Fuels: Coal, oil (petroleum), and natural gas are derived from ancient organic matter and are commonly used as energy sources.
2. Biomass: Organic materials like wood, crop residues, and animal waste can be burned as fuels.
3. Hydropower: Flowing water is harnessed to generate electricity.
4. Wind Energy: The kinetic energy of the wind is converted into electricity through wind turbines.
5. Solar Energy: Sunlight is captured and converted into electricity or used for heating.
6. Geothermal Energy: Heat from the Earth's interior is utilized for heating and electricity generation.
These resources contribute to our energy needs and can be categorized as renewable or non-renewable based on their replenishment rates.
5. What is meant by forests?
Ans. Forests are large areas covered with a dense growth of trees and other vegetation. They play a crucial role in maintaining ecological balance, supporting biodiversity, and providing various ecosystem services, such as oxygen production, carbon sequestration, and habitat for numerous plant and animal species. Forests also serve human needs by offering timber, non-timber forest products, and recreational spaces.
6. What are the uses of forests?
Ans. Forests serve various essential purposes, including:
1. Biodiversity: Forests provide habitats for a wide variety of plant and animal species, supporting biodiversity.
2. Oxygen Production: Trees in forests contribute to the production of oxygen through photosynthesis.
3. Carbon Sequestration: Forests act as carbon sinks, helping to absorb and store carbon dioxide, thereby mitigating climate change.
4. Timber and Wood Products: Trees in forests are a source of timber, wood, and other products for construction, furniture, and paper.
5. Medicinal Resources: Many plants in forests have medicinal properties, contributing to traditional and modern medicine.
6. Water Regulation: Forests play a role in regulating water flow, preventing floods, and maintaining water quality.
7. Recreation and Tourism: Forests provide recreational spaces for activities like hiking, camping, and ecotourism.
8. Cultural and Spiritual Significance: Forests often hold cultural and spiritual value for indigenous communities.
9. Climate Regulation: Forests influence local and global climates by regulating temperature, humidity, and precipitation.
10. Erosion Control: The roots of trees in forests help prevent soil erosion.
11. Renewable Energy: Biomass from forests can be used as a source of renewable energy.
Sustainable forest management is crucial to balance these uses and preserve the long-term health and functionality of ecosystems.
7. Are minerals to be found in seas and on the seabed as they are found inside the earth?
Ans. Yes, minerals are found in seas and on the seabed, similar to their presence inside the Earth. The seabed contains various minerals, including valuable resources like manganese nodules, polymetallic sulphides, and other mineral deposits.
8. Why are all minerals not ores?
Ans. Not all minerals are ores because ores are minerals that contain valuable substances in quantities and forms that can be extracted profitably. While all ores are minerals, not all minerals meet the economic criteria to be considered ores.
9. What is meant by metal mineral and non-metal mineral?
Ans. A metal mineral is a mineral that contains a valuable metal element, such as iron, copper, or gold. A non-metal mineral, on the other hand, does not contain valuable metals but may have other industrial uses, like gypsum or quartz. The classification depends on the elemental composition of the mineral.
10. Why is mineral oil called ‘liquid gold’?
Ans. Mineral oil is called "liquid gold" due to its versatile and valuable properties. It is a colourless and odourless oil derived from petroleum, and its widespread use in various industries, including cosmetics, pharmaceuticals, and lubricants, contributes to its high economic value and the nickname "liquid gold."
11. Why is coal called 'black gold'?
Ans. Coal is called "black gold" because, like gold, it has significant economic value. It has been a historically vital energy resource, particularly during the Industrial Revolution. The term highlights the importance of coal as a valuable and abundant natural resource that played a crucial role in powering industries and economies.
12. What would happen if underground mineral resources are exhausted?
Ans. If underground mineral resources are exhausted, it could lead to a scarcity of essential materials for various industries. This may result in increased prices, economic challenges, and a need for alternative sources or materials. Additionally, it could spur innovation in recycling, exploration of new deposits, and development of substitutes for the depleted minerals.
13. Why is natural gas an eco-friendly fuel?
Ans. Natural gas is considered eco-friendly because it produces fewer greenhouse gas emissions compared to other fossil fuels like coal and oil when burned for energy. It releases lower levels of carbon dioxide (CO2) and other pollutants, contributing to reduced air pollution and a smaller carbon footprint. However, the extraction and transportation processes may still have environmental considerations.
14. What useful things will we have to do without if rubber is no longer available?
Ans. If rubber is no longer available, we would have to do without essential products such as tires for vehicles, machinery, and bicycles. Additionally, various everyday items like rubber gloves, elastic bands, and many types of footwear would become scarce, impacting industries and daily life. Finding alternative materials with similar properties would be crucial.
15. What are the adverse effects of clearing of forest or cutting down trees?
Ans. The adverse effects of clearing forests or cutting down trees include loss of biodiversity, disruption of ecosystems, soil erosion, altered water cycles, increased greenhouse gas emissions, and the loss of habitats for many species. Deforestation contributes to climate change, reduces air and water quality, and poses significant environmental challenges.
16. Write down the characteristics of Compressed Natural Gas.
Ans. Compressed Natural Gas (CNG) has the following characteristics:
1. Composition: Mainly consists of methane (CH4), with small amounts of other hydrocarbons.
2. Colour and Odour: CNG is colourless and odourless in its natural state. An odorant is often added for safety reasons.
3. State: It is in a gaseous state at room temperature and is stored under high pressure to increase its energy density.
4. Clean Burning: Produces fewer emissions compared to traditional fuels, contributing to lower air pollution.
5. Energy Content: High energy content per unit volume, making it an efficient fuel for vehicles and industrial applications.
6. Storage: Requires special storage tanks designed to withstand high pressures.
7. Safety: CNG is lighter than air, so in case of a leak, it disperses quickly, reducing the risk of ignition.
8. Renewable Aspect: Biogas, derived from organic waste, can be purified and used as CNG, providing a renewable source of fuel.
9. Vehicle Conversion: Many vehicles can be converted to run on CNG, contributing to the use of alternative and cleaner fuels in transportation.
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