NCERT Questions & Answers + Important Extra Questions
NCERT Textbook Questions
Q1. Multiple Choice Questions
(i) Which one of the following minerals is formed by decomposition of rocks, leaving aite residual mass of weathered material?
(a) Coal (b) Bauxite (c) Gold (d) Zinc
(ii) Koderma, in Jharkhand, is the leading producer of which one of the following minerals?
(a) Bauxite (b) Mica (c) Iron ore (d) Copper
(iii) Minerals are deposited and accumulated in the strata of which of the following rocks?
(a) Sedimentary rocks (b) Metamorphic rocks (c) Igneous rocks (d) None of the above
(iv) Which one of the following minerals is contained in the Monazite sand?
(a) Oil (b) Uranium (c) Thorium (d) Coal
Q2. Answer the following questions in about 30 words
(i) Distinguish between the following in not more than 30 words: (a) Ferrous and non-ferrous minerals (b) Conventional and non-conventional sources of energy.
Ans.
(a) Ferrous minerals: Contain iron — iron ore, manganese, chromite, nickel, cobalt. Form the backbone of metallurgical industries. India is rich in ferrous minerals.
Non-ferrous minerals: Do not contain iron — copper, bauxite (aluminium), lead, zinc, gold, silver, tin. Used in electrical, chemical, and alloy industries.
(b) Conventional energy sources: Traditional sources used for a long time — coal, petroleum, natural gas, firewood, cattle dung. Most are non-renewable and cause pollution.
Non-conventional energy sources: Newer, cleaner alternatives — solar, wind, tidal, geothermal, biogas, nuclear energy. Most are renewable and environmentally friendly.
(ii) What is a mineral?
Answer
A mineral is a naturally occurring, homogeneous substance with a definite internal structure and chemical composition. Minerals are formed by geological processes and are found in various types of rocks. They are an indispensable part of our lives — from a simple cooking vessel to a space shuttle, everything is made from minerals. There are over 3,000 known minerals, but only a few hundred are commercially useful.
(iii) How are minerals formed in igneous and metamorphic rocks?
Answer
In igneous and metamorphic rocks, minerals are formed when molten magma (lava) cools and solidifies. As magma rises towards the earth's surface, it cools at different rates. Minerals that cool slowly at great depth form large crystals (e.g., granite). Those that cool quickly on the surface form small crystals (e.g., basalt). Sometimes magma is forced into cracks and joints of existing rocks — when it solidifies, minerals form in veins and lodes. Tin, copper, zinc, lead, and gold are commonly found in veins and lodes in igneous rocks.
(iv) Why do we need to conserve mineral resources?
Answer
We need to conserve mineral resources because: (i) Minerals are non-renewable — they take millions of years to form and cannot be replenished quickly. (ii) The total volume of minerals is finite and exhaustible. (iii) Current rates of extraction and consumption are unsustainable — many minerals may be exhausted within a few decades. (iv) Future generations have an equal right to these resources. (v) Mining causes environmental degradation — deforestation, soil erosion, water pollution. Conservation through recycling, using substitutes, reducing waste, and developing new technologies is essential.
Q3. Answer the following questions in about 120 words
(i) Describe the distribution of coal in India.
Ans. Coal is India's most important energy resource, accounting for over 50% of the country's energy needs. Distribution:
(a) Gondwana coal fields (98% of reserves): Found in the river valleys of the Damodar (Jharkhand-West Bengal), Mahanadi (Odisha-Chhattisgarh), Godavari, Son, and Wardha. Major coalfields:
(i) Jharkhand: Jharia (India's richest coalfield), Bokaro, Giridih, Karanpura, Ramgarh.
(ii) West Bengal: Raniganj (oldest coalfield in India).
(iii) Odisha: Talcher, Ib Valley.
(iv) Chhattisgarh: Korba, Singrauli (shared with MP).
(v) Madhya Pradesh: Singrauli, Pench, Kanhan valleys.
(vi) Andhra Pradesh/Telangana: Singareni coalfield (Godavari valley).
(b) Tertiary coal fields (2% of reserves): Found in Meghalaya, Assam, Arunachal Pradesh, and Nagaland in the north-east, and Jammu & Kashmir. This coal is of inferior quality (lignite). Neyveli in Tamil Nadu has significant lignite deposits.
India is the third largest coal producer in the world. Coal India Limited (CIL) is the largest coal-producing company.
(ii) Why do you think that solar energy has a bright future in India?
Answer
Solar energy has a bright future in India because:
(i) Geographical advantage: India is a tropical country, receiving abundant sunlight for most of the year. Most parts receive 4-7 kWh per sq. metre per day of solar radiation — among the highest globally.
(ii) Rajasthan and Gujarat have vast stretches of barren land ideal for solar farms. The Thar Desert alone receives over 300 sunny days per year.
(iii) Declining costs: Solar panel prices have fallen by over 80% in the last decade, making solar power competitive with coal-based electricity.
(iv) Government push: India has committed to 500 GW of renewable energy by 2030. The National Solar Mission targets massive solar capacity expansion. Solar parks like Bhadla Solar Park (Rajasthan) — one of the world's largest — demonstrate India's commitment.
(v) Rural electrification: Solar energy can bring electricity to remote villages where grid power is impractical.
(vi) Environmental benefits: Solar energy produces zero emissions, helping India meet its climate change commitments (Paris Agreement).
(vii) Energy security: India imports over 80% of its petroleum. Solar energy reduces dependence on imported fossil fuels.
Important Extra Questions
How are minerals classified? Give examples of each type.
Answer
Minerals are classified as:
(a) Metallic minerals: Contain metals and can be melted to obtain new products.
— Ferrous (contain iron): iron ore, manganese, chromite, nickel, tungsten, cobalt.
— Non-ferrous (no iron): copper, bauxite, lead, zinc, gold, silver, tin.
(b) Non-metallic minerals: Do not contain metals. Examples: limestone, dolomite, mica, gypsum, salt, potash, sulphur, phosphate, marble, sandstone.
(c) Energy minerals: Used for generating energy. Examples: coal, petroleum, natural gas, uranium, thorium.
Describe the distribution of iron ore in India.
Answer
India has the largest reserve of iron ore in Asia. Distribution:
(i) Odisha: Largest producer — Mayurbhanj, Kendujhar (Keonjhar), Sundergarh districts. High-quality haematite ore. Badampahar mines are famous.
(ii) Jharkhand: Singhbhum district — Noamundi, Gua mines produce high-grade haematite.
(iii) Chhattisgarh: Durg, Bastar, Dantewada districts — Bailadila mines are among the richest in the country. Iron ore is exported to Japan and South Korea.
(iv) Karnataka: Bellary-Hospet region, Baba Budan Hills, Kudremukh (now closed). Second largest producer.
(v) Goa: Was a major exporter, but mining has been restricted due to environmental concerns.
(vi) Maharashtra: Chandrapur, Ratnagiri districts.
India produces both haematite (best quality, 70% iron content, reddish) and magnetite (highest iron content up to 72%, but less abundant, found in Karnataka).
What are the non-conventional sources of energy? Why is there a need to develop them?
Answer
Non-conventional (alternative/renewable) energy sources include:
(i) Solar energy — photovoltaic cells and solar thermal plants. (ii) Wind energy — wind farms (India is 4th largest wind power producer; Tamil Nadu, Gujarat, Rajasthan lead). (iii) Biogas — from animal and plant waste; provides fuel and manure. (iv) Tidal energy — from ocean tides (potential sites: Gulf of Khambhat, Gulf of Kutch). (v) Geothermal energy — from earth's internal heat (Puga Valley in Ladakh, Manikaran in Himachal Pradesh). (vi) Nuclear energy — from uranium and thorium (Tarapur, Rawatbhata, Kalpakkam, Narora, Kakrapar, Kaiga).
Need to develop them: (i) Conventional sources (coal, petroleum) are fast depleting. (ii) Fossil fuels cause pollution and climate change. (iii) India imports large quantities of petroleum, draining foreign exchange. (iv) Renewable sources are clean and sustainable. (v) They can bring energy to remote areas. (vi) India has enormous renewable energy potential (solar in Rajasthan, wind in Tamil Nadu).