Is Matter Around Us Pure? - Class 9 Science Notes
Introduction How do we define pure? The use of word ‘Pure’ in science means that all the constituent particles of a substance are the same in their chemical nature. That is it is made up of same type of particles and is hence pure. A pure substance therefore has same chemical properties for all its constituents. A pure substance consists of only one type of atom, molecule, or compound. Example: Diamond, Sulphur, Tin, Crystals of Salt or any other substance that is consistent in its structure....
9 min read →Atoms and Molecules - Class 9 Science Notes
Laws of Chemical Combination Antoine L. Lavoisier laid the foundation of chemical sciences by establishing two important Laws of Chemical Combinations, which are: (i) Law of Conservation of Mass (ii)Law of Constant Proportions Law of Conservation of Mass The law of conservation of mass states the “Mass can neither be created nor be destroyed in a Chemical reaction”. During a chemical reaction, the sum of the masses of the reactant and products remains unchanged. Law of Constant Proportions...
7 min read →Structure of Atoms - Class 9 Science Notes
Introduction Matter is made up of fundamental building blocks, that is atoms and molecules. The existence of different kinds of matter is due to different atoms constituting them. Are atoms really indivisible, as proposed by Dalton? One of the first indication that atoms are not indivisible (means divisible), comes from studying static electricity and the conditions under which electricity is conducted by different substances. Charged Particles in Matter From different experiments, it was...
7 min read →Tissues - Class 9 Science Notes
Introduction In unicellular organisms, a single cell performs all basic functions such as ingestion, digestion, absorption, reproduction, excretion among others. There are no specialized organs to perform these functions. In multi-cellular organisms however, there are specialized group of cells that perform these functions and are called tissues. Each specialized function is taken up by a different group of cells. Since these cells carry out only a particular function, they do it very...
12 min read →Diversity in Living Organisms - Class 9 Science Notes
Introduction - Each organism is different from the other to a lesser or greater extent. - On one hand we have microscopic bacteria of a few micrometers in size, while on other hand blue whale and red wood trees of 30 metres and 100 metres respectively. - Some of pine trees live for thousands of years while insects like mosquito die within a few days. - Life also ranges from colourless or even transparent worms to brightly coloured birds and flowers. Classification Biologist, such as Ernest...
8 min read →Fundamental Unit of Life - Class 9 Science Notes
Introduction What is a cell? A cell is considered as the building block of life. All living organisms are composed of these microscopic units and it is therefore considered as the basic functional and structural unit of all life. Cytology – It is the study of cells . Cells have been studied since a long time now and many scientists have contributed to the knowledge pool of different types of cells. Staining of Cells: Cells can be studied under microscopes by staining them so that we can...
12 min read →Motion - Class 9 Science Notes
Introduction Rest: A body is said to be in a state of rest when its position does not change with respect to a reference point. Motion: A body is said to be in a state of motion when its position change continuously with reference to a point. What is a reference point? Generally, the position of an object needs to be defined with respect to a fixed point in space. This point is often referred to as the origin. Frame of Reference Depending on the frame of reference, an object may appear...
3 min read →Force and Laws of Motion - Class 9 Science Notes
Introduction Force can be called as a push or pull on the object that enables us to do any work. For example in order to open the door we either push or pull it. Similarly, when a drawer is polled or pushed to open or close it forces said to have been applied. Effects of force • It can make a stationary body move • In stop a moving body • It can change the direction of a moving object • It can change the speed of a moving body • Change the shape and size of an object Forces are mainly of two...
4 min read →Gravitation - Class 9 Science Notes
Introduction What is Gravitational Force? Every object in the universe is attracting every other object of the universe. The force of attraction between any two objects in the universe is known as the “force of gravitation”. Gravitational force is a weak force and cannot be observed unless large masses are involved. However, it is a long-range force. According to Newton’s law of gravitation, the force of gravitational attraction between two objects is directly proportional to the product of...
6 min read →Work and Energy - Class 9 Science Notes
The energy required for the life process comes from food. Activities like playing, singing, reading, writing, thinking, jumping, cycling and running require energy. Work Work done on an object is defined as the product of the magnitude of the force acting on the body and the displacement in the direction of the force. The force component F cos θ gives the component of force along the direction that the body is displaced. Cos θ is the angle between the force vector and displacement vector. If...
6 min read →Sound - Class 9 Science Notes
Introduction Sound is a form of energy which produces sensation of hearing in our ears It is produced due to vibration of different objects. Law of conservation of energy is also applicable to sound. Sound travels in the form of wave. Production of Sound Sound is produced when object vibrates. (Vibration means a kind of rapid to and fro motion of an object) The energy required to make an object vibrate and produce sound is obtained from sources like hand, wind, etc. Examples: i. Striking the...
8 min read →Why do we fall ill? - Class 9 Science Notes
What is Health? Health is a state of complete physical, mental and social well-being. It is not merely the absence of diseases. It is a state of complete physical, mental and social well being. Health of a person depends upon one’s personal habits as well as physical and social environment. What are the basic conditions for good health? Proper balanced and nutritious diet. Personal hygiene. Clean environment and surroundings. Healthy air, no pollution in the surrounding. Regular exercise....
12 min read →Natural Resources - Class 9 Science Notes
Introduction Life on the earth depends on the resources like air, water, soil, etc. The resources available on the earth and the energy from the sun are necessary to meet the basic requirement all life forms on the earth. The stock of nature which are useful to mankind are known as natural resources. Example: air, water, soil, minerals, etc. Natural Resources The outer crust of the Earth. Lithosphere Water covers 75% surface of the earth and also found underground. Hydrosphere The air that...
7 min read →Improvement in Food Resources - Class 9 Science Notes
Introduction Food supplies proteins, carbohydrates, fats, vitamins and minerals, which are required for body development, growth and health. Both plants and animals are major sources of food. Green Revolution: Green revolution is a programme introduced in many countries to increase the food production by use of modern technology, proper irrigation, improved seeds, etc. White Revolution: White revolution is a programme in India introduced to increase the production of milk in India. This...
6 min read →Matter in Our Surroundings - Class 9 Science Notes
Introduction Everything in this universe is made up of material which scientists have named “matter”. The air we breathe, the food we eat, stones, clouds, stars, plants and animals, even a small drop of water or a particle of sand – every thing is matter. Matter is defined as having both mass and volume. Modern day scientists have evolved two types of classification of matter based on their physical properties and chemical nature. Some people believed matter to be continuous while others...
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