Chapter 11: Nature’s Treasures
Explore natural resources including air, water, solar energy, forests, soil, rocks, and minerals essential for survival and life on Earth[cite: 4].
1. Air
Air surrounds the Earth as a mixture of gases essential for survival[cite: 4]. We need oxygen present in the air for breathing[cite: 4]. Moving air is termed wind[cite: 4].
Composition of Air
Nitrogen makes up 78%, Oxygen 21%, and Argon, Carbon Dioxide, and other gases make up 1%[cite: 4].
Wind & Windmills
Moving air rotates windmills to pull water, run flour mills, or generate electricity[cite: 4].
2. Water
Water covers roughly two-thirds of the Earth's surface, predominantly in oceans and seas as saline water[cite: 4]. Freshwater is limited and found in ice sheets, snow, underground, rivers, and lakes[cite: 4].
| Water Type | Sources | Usability |
|---|---|---|
| Saline Water | Oceans and Seas[cite: 4] | Not fit for domestic, agricultural, or industrial use[cite: 4]. |
| Freshwater | Ice sheets, snow, underground, lakes, rivers, ponds, and wells[cite: 4] | Essential for drinking, cooking, bathing, washing, and agriculture[cite: 4]. |
3. Energy from the Sun
The Sun is the primary source of energy on Earth[cite: 4]. Plants utilize sunlight to produce food, and animals depend on plants or other animals for energy[cite: 4].
Mathematical expression for solar energy efficiency estimation:
$$\text{Efficiency (\%)} = \left( \frac{\text{Energy Output}}{\text{Solar Energy Input}} \right) \times 100$$Solar panels capture sunlight to produce electricity, while solar cookers and water heaters use direct heat[cite: 4].
4. Forests
Forests are large areas dense with herbs, shrubs, and trees, providing natural habitat, food, and shelter for wild animals, birds, and insects[cite: 4].
5. Soil, Rocks, and Minerals
Soil forms over thousands of years through the disintegration of rocks by the action of the Sun, water, and living organisms[cite: 4]. Plant roots hold soil to prevent erosion, while fallen leaves decay into nutrients[cite: 4].
Soil & Biodiversity
Air spaces between soil particles enable root growth and respiration[cite: 4]. Earthworms loosen soil naturally[cite: 4].
Rocks & Uses
Granite, sandstone, marble, slate (roofing), and laterite (bricks) are used in construction[cite: 4].
Minerals & Metals
Rocks consist of minerals[cite: 4]. Metals like iron, copper, gold, and aluminium are extracted for electronics and manufacturing[cite: 4].
6. Exercises & Questions
Q1. What is wind, and how is it used to produce electricity?
Answer: Moving air is called wind[cite: 4]. Wind turns the blades of windmills in windmill farms (e.g., Muppandal Wind Farm), which drives generators to produce electricity[cite: 4].
Q2. How is soil formed, and why is air space in soil important?
Answer: Soil is formed by the disintegration of rocks by sunlight, water, and living organisms over thousands of years[cite: 4]. Air space between soil particles provides oxygen for plant root respiration and space for roots to grow easily[cite: 4].
7. MCQ Quiz
Q1. What percentage of air is composed of Oxygen?