Nature’s Treasures

11.1 Air

Air is an invisible, odourless gas that surrounds the Earth and is essential for the survival of all living beings. It is a mixture of several gases, primarily nitrogen (78%), oxygen (21%), and small amounts of argon, carbon dioxide, and other gases. Oxygen is crucial because living organisms need it to perform vital functions such as respiration. Humans and animals breathe in oxygen and breathe out carbon dioxide. Plants, on the other hand, use carbon dioxide for photosynthesis and release oxygen. We cannot survive without oxygen for even a few minutes, although we can live without food or water for several days. Air is also responsible for various natural phenomena such as rustling of leaves, movement of clothes on a line, or fluttering pages of a book when a fan is switched on. When air moves, it is called wind. Wind can be gentle like a breeze or strong like a storm. Wind energy is harnessed by devices such as windmills, which rotate when wind blows and can be used to generate electricity, pump water, or run flour mills. Windmill farms, like Muppandal in Tamil Nadu, Jaisalmer in Rajasthan, and Brahmanvel in Maharashtra, are large areas with many windmills that produce electricity using wind energy. Breathing exercises, like taking deep breaths and slowly exhaling, help bring more fresh air into the lungs, promoting good health. Holding breath for a long time is difficult because the body needs a constant supply of oxygen to function properly. This section introduces the importance of air as a natural resource necessary for life and energy.

• Air is a mixture of gases: 78% nitrogen, 21% oxygen, and 1% argon, carbon dioxide, and others.
• Oxygen in air is essential for respiration and survival of living beings.
• Moving air is called wind; it can be gentle (breeze) or strong (storm).
• Wind energy can be harnessed using windmills to generate electricity and perform mechanical work.
• Breathing exercises help increase oxygen intake and promote health.
• Humans cannot survive without oxygen for even a few minutes.
• 📌 Air: A mixture of gases surrounding the Earth.
• 📌 Oxygen: A gas in air essential for respiration.
• 📌 Wind: Moving air caused by natural forces.

11.2 Water

Water is a vital natural resource essential for all forms of life. It is used for drinking, cooking, bathing, washing, cleaning, agriculture, and industrial purposes. Freshwater is found in rivers, lakes, ponds, glaciers, and underground sources, but most of the Earth's water is saline and found in oceans, which is not suitable for drinking or irrigation. Freshwater sources are limited and precious, so it is important to use water carefully and avoid wastage. Water wastage can occur during activities such as hand washing, washing clothes and utensils, taking showers, cooking, gardening, and brushing teeth. Simple measures like turning off taps when not in use, fixing leaks, and recycling water can reduce wastage. Water pollution is a serious problem caused by dumping waste, plastic, and industrial effluents into water bodies, making water unfit for consumption. Rainwater harvesting is an ancient and effective method of conserving water by collecting and storing rainwater for later use. Traditional structures like stepwells (Bawadi or Vav) in Rajasthan and Gujarat demonstrate water harvesting by storing rainwater and seepage water. Conserving water and preventing pollution are essential for sustaining life and ensuring availability of clean water for future generations.

• Water is essential for drinking, cooking, cleaning, agriculture, and industry.
• Most of Earth's water is saline and found in oceans; freshwater is limited.
• Water wastage occurs in daily activities but can be reduced by simple measures.
• Water pollution from waste and industrial effluents harms living beings.
• Rainwater harvesting collects and stores rainwater for future use.
• Traditional water harvesting structures like stepwells are examples of conservation.
• 📌 Freshwater: Water suitable for drinking and irrigation, found in rivers, lakes, and underground.
• 📌 Saline water: Saltwater found in oceans, not fit for drinking or farming.
• 📌 Water pollution: Contamination of water bodies by waste and harmful substances.