Oxford Six Class Science Notes [PDF]

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Unit 1 Introduction of Science 1. What is science? The study of the things and events that take place around us is called science.

2. Who is scientist? A person who studies science is called scientist.

3. What is laboratory? A laboratory is a place where a scientist works and uses many instrument.

4. How does a scientist find answers to problems? A scientist tries to find answers to by performing experiments and collecting more information then he or she write down the result and draws conclusion from them.

Unit 2 Living Things 1. What is biology? The study of living things is called biology.

2. What is an organism? An organism is a living thing.

3. Describe the structure of a cell? The structure of a cell, A cell is consists of a cell membrane, Cytoplasm, vacuole and nucleus etc.

4. What is the function of the nucleus in a cell? Nucleus is a control center of a cell. It controls the whole working of a cell.

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5. How do green plants make their food? Green plants make their food by a process, called photosynthesis. In this process, they take light from the sun, carbon dioxide from the air, and water from the soil and chlorophyll which is present in their leaves, to make their food.

6. What is

respiration?

It is a process by which we take oxygen from the air. This oxygen combines with food and produces the energy. Carbon dioxide is produced during this process.

7. What is excretion? The process by which waste and poisonous materials are removed from the body is called excretion.

Unit 3 water 1. What is composition of water? Write its chemical formula? Water is the made up of two gases, oxygen, and hydrogen. Its chemical formula is H2O.

2. Why can fish and other water animals and plants breathe in water? Because fresh water contains dissolved oxygen which water animal breath.

3. Define the term melting, boiling, evaporation, condensation, freezing. ∗ Melting:The temperature at which things melt is called melting. ∗ Boiling:The temperature at which liquid things boil is called boiling point. ∗ Evaporation:When water is heated, it changes into water vapors. This is called evaporation. ∗ Condensation:In this process, steam changes into liquid water. Science Notes

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∗ Freezing. When water is cooled, it freezes into form of ice. This is called freezing.

4. How can you find out whether a sample of water is pure or not? Pure water boils at 100C. If there are some impurities in water, it will boil at high temperature than 100C.

5. What is hard water? If water contains some impurities then it is called hard water.

6. What is the hardness of water due to? The hardness of water is due to some chemicals that get. Dissolved in rain water when it falls.

7. What are the properties of pure water? ∗ Pure water has no colour. ∗ It freezes at 00C. ∗ It boils at 1000C. ∗ It is a bad conductor of electricity. ∗ It is a very good solvent.

8. What are some of the common impurities in water? Water contains many impurities such as mud, sand, Bacteria, mineral salt and remains of dead plant and animals.

9. How can water be purified in the laboratory? In the laboratory, water can be purified by a process called distillation.

10. Write three ways in which water become polluted? Causes of water pollution. ∗ Dirty water from houses and farms. ∗ Waste liquid from factories.

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∗ Oil spills from oil tankers at sea.

Unit 4 Air 1. What is the atmosphere? The earth is surrounded by a layer of air which is like a huge ocean. It extends to almost hundreds of kilometers above the surface of the earth. This ocean of air is called the atmosphere.

2. What is the percentage of gases found in the atmosphere? The atmosphere is made up of several layers of air containing mixture of different gases. About one fifth of the air is oxygen, near four fifth consist of nitrogen, and the rest is made up of carbon dioxide and small amount of other gases.

3. Name the layer of the atmosphere? Which layer is the most important for living things? There are four layer of atmosphere. ∗ Iroposphere ∗ Iropopause ∗ Stratosphere ∗ Lonosphere. Stratosphere: - Stratosphere is the most important layer for living things.

Unit 5 Pollution 1. What does the earth give us? The Earth gives us everything we need to live. It gives us air to breathe, food to eat and water to drink. It gives us materials for our clothes and for building our houses. Farmers grow crops to give us the food that we need.

2. What are the things that have a bad effect on the earth? Science Notes

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The number of people living on the Earth is increasing. In order to fulfill the needs of all people, we are trying to grow more and more crops. We are cutting down trees to build houses and roads. We are building new factories and industries. All these things are having a very bad effect on the Earth. Farmers grow crops to give us the food that we need. By growing more and more crops on the same land for many years the plants use up the important minerals in the soil. The soil cannot grow plants any more.

3. Why are plants important for life on earth? Plants provide food for humans and animals. Plants take in carbon dioxide gas from the air to make their food. They give out oxygen gas. Humans and animals breathe in oxygen gas and breathe out carbon dioxide gas.

4. How are trees useful to us? Trees provide food and wood for making the furniture. Without trees the soil dries up and cracks. Trees absorb water from the soil. Extra water evaporates from the surface on the leaves. Trees affect the rainfall of an area.

5. Define the following terms: environment, pollution, pollutant. The natural world that surrounds a living thing is called environment. The environment affects the growth and development of living things. When some unwanted and harmful thing appears in an environment we call it pollution. There are different types of Pollution noise' air' water and Land. Anything which harms the environment is called a pollutant.

6. Name the different types of pollution that are found in the environment. There are different types of Pollution noise' air' water and Land. Air, water and land can become polluted by harmful chemicals, or dirty waste materials that may be solid, liquid or gas. Unwanted loud sounds can cause noise pollution.

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7. Name the different sources of air pollution. Air contains many harmful substances near the towns and cities. Harmful gases, smoke and chemicals come from factory chimneys. They pollute the air. These are major source of air pollution.

8. How does a river become polluted? When the water comes from the mountains, it’s clean and pure. When it passes alongside a town, chemicals from factories and houses includes into it. When a river reaches near the sea, its water contain full of poisonous. Rivers carry polluted water to the seas and oceans. Ships carry rubbish and waste materials from factories into the sea and put down on the ocean floor.

9. What is an oil spill? What is the harmful effect of an oil spill? Oil spill is the leakage of oil tanker. Oil tankers carry tonnes of oil. If an oil tanker leaks, it creates an oil spill in the sea. Oil kills fish, seabirds and other sea animals.

Unit 6 Energy 1. What is energy? Energy is the Capacity of matter to perform work as the result of its motion or its position in relation to forces acting on it.  Energy is the ability or power to do a particular work.

2. Where does all energy on earth come from? All the energy on Earth comes from the Sun. The Sun's energy is called solar energy. It changes into other kinds of energy when it reaches the Earth.

3. What are fossil fuels? Oil and coal are called fossil fuels.

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4. What is the difference between potential and kinetic energy? The difference between kinetic and potential energy is that kinetic energy produced when atoms is moving and Potential energy is the stored energy of a body due to its position. The relationships between kinetic and potential energy and among the concepts of force, distance, acceleration, and energy can be illustrated by the lifting and dropping of an object.

5. What is chemical energy? When two chemical are mixed with each other then energy produced after reaction is called chemical energy. The energy released after chemical reaction during the decomposition or formation of compounds is called chemical energy. The energy for our body comes from the food we eat. Food contains chemical energy.

6. How does sound energy move? When an object vibrates, it makes the air around it vibrate. The vibrations travel in the air as sound waves. The sound waves move through sound energy from one place to another.

7. What is nuclear fission? Nuclear fission is a process in which atom can be split. The nucleus of a uranium atom can be split into two. This breaking of uranium atom is called nuclear fission. Nuclear energy can be released in two different ways: fission, the splitting of a large nucleus, and fusion, the combining of two small nuclei.

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8. How is solar energy produced? Solar energy is produced by the fusion of hydrogen atoms, which crash into each other, making larger atoms of helium gas.

9. Can energy be made? Every form of energy can change into another form. Energy cannot be made and cannot be destroyed.

Unit 7 Electricity Science Notes

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1. How do we use electricity? We use the electricity by the electronic device. There are number of devices which uses for different purpose such as for lighting, Heating and many other purpose etc. All the electronic device and machines run and work by the electricity.

2. How is the Electricity produced in power station? Electricity produced in power station by the generator and generator also use the energy such as running water, burning fuel or nuclear energy which is run inside the machines and convert into electrical energy.

3. How is an electric current produced? An electric current is a movement of charges. Electric current produced when electrons move and pushed to each other. Each electron carries only small amount of energy. Inside a wire there are millions and millions of electrons make a strong push. Due to this we get the work done.

4. What is an electric circuit? The pathway by which an electric current moves along the wires is called an electric circuit.

5. What is lighting? When positive and negative charges in the clouds jump towards each other through the air. The electric current makes a spark which is seen as a flash of lightning. Electric Lines of Force Electric lines of force indicate the direction in which a positive test charge would move if it were placed in an electric field. The diagram on the left shows lines of force for two positive charges that repel each other. A positive test charge would be pushed away from both charges. The diagram on the right shows lines of force for two unlike charges that attract each other. A positive test charge would be pushed away from the positive charge and toward the negative charge.

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Magnetic Fields and Electricity Hans Christian Oersted predicted in 1813 that a connection would be found between electricity and magnetism. In 1819 he placed a compass near a current-carrying wire and observed that the compass needle was deflected. This discovery demonstrated that electric currents produce magnetic fields. As shown here, the magnetic field lines circle around the current-carrying wire.

Incandescent Lamp In an incandescent lamp, electric current flows through a thin tungsten wire called a filament. The current heats the filament to about 3000°C (5400°F), which causes it to emit both heat and light. The bulb must be filled with an inert gas to prevent the filament from burning out. For many years incandescent lamps were filled with a mixture of nitrogen and argon. Recently the gas krypton has been used because it allows the filament to operate at a higher temperature, which produces a brighter light.

Unit 8 Magnetism 1. What is an atom made up of? Atoms are made up of protons, neutrons and electrons.

2. What are ions? How are ions formed? Ions are the individual atom or group of atoms. Ions formed when individual atom, or group of atoms having a net electric charge (either positive or negative) due to loss or gain of one or more electrons.

3. What is electrostatic induction? The process in which positive charge object produce the negative charge when it’s brought close to a neutral object. This process is called electrostatic induction.

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4. How can a body be tested for the presence of a charge? A body can be tested for a charge in the laboratory with the help of an instrument called a gold leaf Electroscope.

5. What is lightning? When positive and negative charges in the clouds jump towards each other through the air. The electric Current makes a spark which is seen as a flash of lightning.

6. What is an electric circuit? The pathway along which charged particles move is called an electric circuit.

7. What are conductors? Materials that allow an electric charge to pass along them are called conductors. Metals are good conductors of electricity.

8. What is magnetism? Magnetism is a force which appears between magnets and magnetic materials like steel and iron. For example, a magnet will attract steel pins and iron nails brought near it.

9. What is the difference between a temporary and a permanent magnet? A piece of steel or iron which keeps magnetic properties is called a permanent magnet. When piece of iron becomes magnetized when it is touched by magnet, which means magnetism has been induced in it. But when it is pulled away from the magnet, it loses its magnetism. This type of magnet is called a temporary magnet.

10. What is a magnetic field? The area around a magnet in which its magnetic force acts is called a magnetic field.

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11. What is a switch? How does it work? Switch is a bridge in which electric current flow along the wire. An electric current can be turned on and off by a switch. When you turn the switch on, a small metal piece inside the switch completes the circuit, and the current flows along the wires. When you turn the switch off, the metal piece moves away from the wire, and the electric current stops flowing.

Unit 9 The Earth 1. What is the earth? What is the shape of the earth? The Earth is the fifth-largest planet of the Solar System. The shape of the Earth is a geoid, it is round but slightly flattened at the top and bottom.

2. Name the layer of the earth? There are three layer of the earth. a) Curst b) Mantle c) Core Inner core & Outer core

3. What are the phases of the moon? The Moon revolves around the Earth and completes the circle in 29.5 days. During revolving the earth it seems in different shapes. Some time it seems full moon and some time it seems slice of the moon. Sometimes we see no Moon at all. The sections of the reflecting surfaces of the Moon are called phases of the Moon.

4. What cases the change in seasons? The change in seasons is caused by the revolution of the Earth around the Sun in an oval path.

Unit 10 Atmosphere and Weather 1. What is the atmosphere? Atmosphere is the layer of the air around the earth.

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2. Name the layers of the atmosphere? Thermosphere Mesosphere Ozone layer Stratosphere Troposphere Ionosphere Importance of the Tropopause Atmosphere

Without atmosphere, there would be no life on Earth. The atmosphere consists of layers of gases that support life and provide protection from harmful radiation.

3. Which layer of the atmosphere has weather? How high is it? The atmosphere can be divided into a series of layers, each layer based on the air temperature at different altitudes.

4. What is air made up of? Air is the made up of different gases, which are invisible. We cannot see them. Nitrogen and oxygen are the two important gases in air.

5. How does the atmosphere protect the earth from becoming too hot? Atmosphere blocks the harmful rays of the sun and some reflected back into the space and some are absorbed by the clouds and dust particles. So due to this earth is not become too hot.

6. What is wind? How are winds caused? When air moves (or blows) then it’s called the wind. It caused by the temperature of the layer.

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7. What is a thermal? When air heats up it expands and becomes lighter then begins to rise. This rising air is called a thermal.

8. What is a low-pressure area? In a place where the air is warm, the air pressure will be less than the surrounding area. This area is called a low pressure area.

9. What is the summer monsoon? In summer the land warms up more quickly than the sea. A large low pressure area forms over the land. Cool air from the sea blows towards the land. This blow of air towards the land is called summer monsoon.

10. What is snow? Snow is the ice crystal flakes. Ice crystals in a cloud join together to form snowflakes. When snowflakes become large and heavy, they fall to the ground as snow.

Unit 11 Space, Star and Planets 1. What are nebulae? Nebulae are the clouds of gas and dust in space. These clouds are called nebulae.

2. How are stars formed? Stars are formed in the nebulae. The mass of nebulae particles becomes tightly packed and pulled by the force of gravity. The temperature rises to over one million degrees. The molecules of hydrogen gas begin to join up to make helium gas molecules and produce a lot of energy in the form of heat and light. This mass of gas and dust begins to shine. A star is formed.

3. What is a galaxy? An island of stars spinning through space is called a galaxy.

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4. What are planets? Bodies that go around the Sun are called planets. (An astronomical object that orbits a star and does not shine with its own light)

5. What is the Solar System made up of? The Sun and all the planets and moons make up the Solar System. (The Sun and all the planets, satellites, asteroids, meteors, and comets that are subject to its gravitational pull)

6. What are planets and moons made of? Scientists think that the planets and their moons were made from the same gas cloud that formed the Sun.

7. What is an asteroid? An asteroid is a lump of rocky material in space. They are going around the Sun in their own orbits like small planets.

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