Class 9 Health, Population and Environment Note
1. All the things present in nature which are utilized by the living organisms for their survival and growth are together called natural resources. For example: plants, animals, sunlight, water, minerals and fossil fuels are natural resources.
2. The concept that natural resources should be kept in the existence state without disturbing their quantity and quality is called absolute conservation.
3. Perpetual resources is that resources which never depletes and never ends. So they are also called unlimited resources. They do not get exhausted due to utilization. Perpetual resources quantity is maintained naturally by the natural phenomenon. Maximum utilization of these resources quantity is maintained naturally by natural phenomenon. For e.g.: Tides, Solar energy etc
4. Renewable resources can be renewed or regenerated again and again its utilization. These types of resources are regenerated due to natural process of formulation in the nature. Plants, fish, fresh air are various biological resources are renewable resources.
5. Non renewable resources are those which cannot be regenerated once finished. These resources are limited in nature. Natural oil and minerals are its examples. The formation of these resources takes millions of years.
6. Water found in the surface of earth is called ground water. Ground water is available in the ocean, sea, rivers, Lake Etc. We have more than 6000 rivers and rivulets in Nepal. Some rivers like Koshi, Gandaki, and Karnali are perennial rivers.
7. A mineral is a non metallic or metallic solid that occurs naturally on the earth’s crust. Examples of non metallic minerals are salt, clay, silicates, sand and gypsum. Minerals are formed and modified as a result of the process taking place over millions of ears in the earth rock cycle.
8. The process of using waste products again and again is known as reuse. A resource can be used over and over again without changing is form. The reuse reduces the consumption of resources.
9. Re-cycling is a method of using the same material by processing it and bringing it back to the same form or other. The articles made of iron and aluminium and other metals can ne recycled again and again.