Minerals and Energy Resources — NCERT Solutions

Answer:

A mineral is a naturally occurring substance that has a definite chemical composition and physical properties. Minerals are formed by natural processes and are found in various types of rocks — igneous, sedimentary, and metamorphic.

They are homogeneous solids with a definite internal structure. Minerals are indispensable for industrial development. Examples include iron ore, bauxite, mica, coal, and petroleum.

Given: Formation of minerals in igneous and metamorphic rocks.

In Igneous Rocks:
Minerals are formed when magma (molten rock material) cools and solidifies. During the cooling process, minerals crystallise and are deposited. They occur in cracks, crevices, faults, and joints. The smaller occurrences are called veins and the larger ones are called lodes. Examples: tin, copper, zinc, lead.

In Metamorphic Rocks:
Minerals are formed when igneous or sedimentary rocks undergo great heat and pressure, causing recrystallisation of existing minerals into new forms. Examples: corundum, garnet, and some forms of iron ore such as magnetite are found in metamorphic rocks.

Conclusion: In both rock types, minerals are found in veins and lodes formed by the cooling of magma or by recrystallisation under heat and pressure.

Given: The need for conservation of mineral resources.

Reasons for Conservation:

1. Limited and non-renewable: Minerals are formed over millions of years by geological processes. Once exhausted, they cannot be replenished in the near future.

2. Rapid depletion: Increasing industrialisation and modernisation have led to rapid consumption of mineral resources.

3. Economic importance: Minerals are the backbone of industrial development. Their depletion would adversely affect the economy.

4. Environmental concerns: Indiscriminate mining causes land degradation, deforestation, and pollution.

5. Future generations: Resources must be conserved so that future generations can also benefit from them.

Measures: Recycling of metals, use of improved technologies to reduce wastage, and finding substitutes are some ways to conserve minerals.

Conclusion: Judicious use of mineral resources is essential for sustainable development.

Given: Distribution of coal in India.

Introduction: Coal is the most abundantly found fossil fuel in India. It is the most important source of energy for the country. India is one of the world's largest producers of coal.

Types and Distribution:

1. Gondwana Coal (about 200 million years old):
This is the most important type and accounts for the bulk of India's coal reserves.

• Damodar Valley (West Bengal–Jharkhand): This is the most important coal belt. It includes Raniganj (West Bengal), Jharia, Bokaro, and Giridih (Jharkhand). Jharia is the most important coalfield.
• Godavari, Mahanadi, Son, and Wardha valleys also contain coal deposits.
• Major states: Jharkhand, Odisha, Chhattisgarh, West Bengal, Madhya Pradesh, Telangana, and Maharashtra.

2. Tertiary Coal (about 55 million years old):
Found in the north-eastern states.

• Meghalaya, Assam, Arunachal Pradesh, and Nagaland.

Conclusion: Coal is unevenly distributed in India, with the major reserves concentrated in the peninsular plateau region (Gondwana coalfields). The north-eastern coalfields are smaller but significant for the region.

Given: Prospects of solar energy in India.

Introduction: Solar energy is the energy obtained from the sun's radiation. It is a renewable and non-polluting source of energy.

Reasons why solar energy has a bright future in India:

1. Tropical location: India is a tropical country and receives sunshine for most of the year. It has enormous potential for solar energy development.

2. Vast sunny areas: States like Rajasthan, Gujarat, and other semi-arid regions receive intense solar radiation throughout the year, making them ideal for solar farms.

3. Photovoltaic technology: Solar energy can be converted directly into electricity using photovoltaic cells. This technology is becoming cheaper and more efficient.

4. Rural electrification: Solar energy can be used to provide electricity to remote and rural areas where conventional power supply is difficult and expensive.

5. Reducing dependence on fossil fuels: India imports a large amount of petroleum. Solar energy can reduce this dependence and save foreign exchange.

6. Environment-friendly: Solar energy does not cause pollution and helps in reducing carbon emissions, contributing to a cleaner environment.

7. Government initiatives: The National Solar Mission (part of the National Action Plan on Climate Change) aims to promote solar energy use across the country.

Conclusion: Given India's geographical location, vast land area, and the need for sustainable energy, solar energy indeed has a very bright future in India. It can help meet the growing energy demands while protecting the environment.

ACROSS:

1. A ferrous mineral (9 letters): MANGANESE
2. Raw material for cement industry (9 letters): LIMESTONE
3. Finest iron ore with magnetic properties (9 letters): MAGNETITE
4. Highest quality hard coal (10 letters): ANTHRACITE
5. Aluminium is obtained from this ore (7 letters): BAUXITE
6. Khetri mines are famous for this mineral (6 letters): COPPER
7. Formed due to evaporation (6 letters): GYPSUM

DOWN:

1. Found in placer deposit (4 letters): GOLD
2. Iron ore mined in Bailadila (8 letters): HEMATITE
3. Indispensable for electrical industry (4 letters): MICA
4. Geological Age of coal found in north-east India (8 letters): TERTIARY
5. Formed in veins and lodes (3 letters): TIN

Note: The crossword answers are based on the clues provided and the chapter content on Minerals and Energy Resources.