Points to remember PR 2.docx.PDF

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: Inte...

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 Miscible: When two liquids mix with each other. Immiscible: When two liquids did not mix with each other. Factors affecting the solubility of a substance are 1. Temperature: With the increase in the temperature the solute will dissolve faster in the solvent. 2. Stirring: With the increase in the stirring; solute will dissolve faster in the solvent. 3. Particle size : Smaller particles of solute will dissolve faster than the larger particles. Sub topic: Properties of substance. a) Thermal conductivity: Substances that carry heat easily are good conductors of heat like Iron, copper,gold, silver. Those substances that are not good carriers of heat are called insulators like rubber, wood, cloth etc. b) Electric conductivity: Those substances that can carry electricity are conductors like aluminium, copper. Used to build the wires. Some substances which cannot carry electricity are called insulators like rubber, wood. Sub topic: Expansion and contraction of matter Caren was trying to open the lid of a jam bottle. She kept trying but was not able to open it. She asked her mother to help her to open the lid. She ran the lid of the jar under hot water for a while and was able to open it easily. How do you think doing this would have made the opening of the jar easier? a. The hot water contracted the lid. a. The lid expanded due to hot water. When an object is heated, it expands and increase in size or volume. When it cooled, it contracts and decrease in size or volume.