DOC-20241231-WA0000.PDF

2. Water: When it rains in the hilly areas, the soil gets washed away towards the plains. The running water deposits the mineral-rich soil in the riverbed and over the years this deposition of soil can change the course of the river. This can lead to floods which cause the destruction of life and pr...

2. Water: When it rains in the hilly areas, the soil gets washed away towards the plains. The running water deposits the mineral-rich soil in the riverbed and over the years this deposition of soil can change the course of the river. This can lead to floods which cause the destruction of life and property. Water erosion leads to loss of agricultural potential. 3. Overgrazing: When cattle are allowed to graze on the same field repeatedly, all the available grass, including the roots are eaten by them. This makes the topsoil vulnerable to wind and flowing water, leading to soil erosion. 4. Deforestation: Humans have taken land from the forest to cultivate in order to feed the ever-increasing population and to build houses, industries, etc. Cutting down trees on a large scale for these purposes is deforestation. The roots of trees hold the soil together, thus preventing the soil from getting uprooted. When large areas of the forest are cleared, the topsoil is eroded by wind and flowing water. Topic: Rocks and minerals 1.Define: 1. Quarry: A large open area of holes made in Earth from which minerals are extracted. 2. Ore: Natural solid material which contains minerals. 3. Metallurgy: The process of extraction of metals from their ores. 4. Peat: Dead remains of plants, when they rot away forming a thick lumpy brown substance called as peat which later turns into coal. 2.Types of rocks Igneous rocks Earths layer: crust, mantle and core. Crust (mountains, plains), below is mantle and then the core. When Volcano erupts, it cools and solidifies to form igneous rocks. When it flows onto the surface its called lava. 95% of the Earth’s crust is made of igneous rocks. Sedimentary rocks: Sedimentary rocks are always formed in layers. Sedimentary rocks form in areas where water, wind, or gravity deposit sediments. Metamorphic rocks: Rocks are formed due to physical and chemical changes in igneous, sedimentary rocks. They happen due to heat and pressure. 3. Types of minerals 4.List out the name if minerals for following ores: Name of Ore Mineral Haematite Iron Bauxite Aluminium Pyrite Copper Calamine Zinc 5. How is petroleum formed? Petroleum is formed when pressure exerted by heat and weight of the rocks on the piles of dead, rotting plants and animals turns them into liquid oil. Fuels like petrol, diesel, kerosene and natural gas are obtained from petroleum. Topic: States of matter Sub topic: Interconversion of matter Sub topic: Types of changes Reversible and irreversible changes: Changes that can be reversed to get back the original substance is called reversible change.(The change of state of water, melting of wax) Changes that cannot be reversed to get back the original substance is called irreversible change.(Burning of wick of candle/log) Sub topic : Solubility of a substance: Will the materials in the table below dissolve in water? Test the materials and complete the table. Instructions-Complete the Record sheet once the experiment is done. S.NO SUBSTANCES NAME OF THE SUBSTANCE DID IT DISSOLVE? CONCLUSION 1 A SAND NO Immiscible 2 B OIL NO Immiscible 3 C VINEGAR YES Miscible