NCERT Solutions Class 9 Science chapter 1 Matter in Our Surroundings in PDF format free download. The complete solutions of chapter end questions and answers of the questions given within the chapter ( intext questions solutions). NCERT Exemplar provides a helpful hand in understanding the chapter’s concepts. The complete chapter is covered through Questions – Answers from the text book which is given below as online study material.
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Question 1: What is Matter?
Answer 1: 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– each thing is matter.
Question 2: What was the classification of matter by early Indian philosophers?
Answer 2: Early Indian philosophers classified matter in the form of five basic elements – the “Panch Tatva”– air, earth, fire, sky and water. According to them everything, living or non- living, was made up of these five basic elements.
Question 3: What is the classification of matter by modern scientists?
Answer 3: Modern day scientists have evolved two types of classification of matter based on their physical properties and chemical nature.
Question 4: What are the physical properties of matter?
Answer 4: a) Matter is made up of particles like sand. b)The particles of matter are very small – they are small beyond our imagination.
Question 5: What are the main characteristics of Particles of Matter?
Answer 5: a) There is enough space between particles of matter. b) Particles of matter are continuously moving, that is, they possess the kinetic energy. c) The particles of matter have force acting between them. This force keeps the particles together.
Question 6: What is meant by diffusion of matter?
Answer 6: Particles of matter intermix on their own with each other. They do so by getting into the spaces between the particles. This intermixing of particles of two different types of matter on their own is called diffusion.
Question 7: What are the different states of matter?
Answer 7: Matter around us exists in three different states– solid, liquid and gas. These states of matter arise due to the variation in the characteristics of the particles of matter.
Question 8: What are the basic properties of solids?
Answer 8: Solids have a definite shape, distinct boundaries and fixed volumes, that is, have negligible compressibility. Solids have a tendency to maintain their shape when subjected to outside force. Solids may break under force but it is difficult to change their shape, so they are rigid.
Question 9: What are the basic properties of liquids?
Answer 9: Liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid.
Question 10: Which have higher diffusion rate Solids or Liquids?Why?
Answer 10: The rate of diffusion of liquids is higher than that of solids. This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.
Question 11: What are the basic properties of gases?
Answer 11: Gases are highly compressible as compared to solids and liquids. Gases show the property of diffusing very fast into other gases. The particles of gases move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.
Question 12: What is meant by LPG and CNG?
Answer 12: LPG is liquefied petroleum gas (LPG) filled in cylinder that we use in our home for cooking or oxygen supplied to hospitals in cylinders is compressed gas. CNG is Compressed natural gas (CNG) is used as fuel these days in vehicles.
Question 13: We come to know of whatever is being cooked in the kitchen without even entering there, by the smell that reaches our nostrils. How does this smell reach us?
Answer 13: The smell of hot cooked food reaches us in seconds by the diffusion process which is faster in gasses.
Question 14: Why do gases exert pressure on the container?
Answer 14: In the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container, which exert pressure on the walls of the container.
Question 15: Name the three states of water.
Answer 15: Three states of matter – Solid as ice, Liquid as water and Gas as water vapour.
Question 16: What is meant by Melting Point of a solid?
Answer 16: The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
Question 17: What is latent heat?
Answer 17: The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion.
Question 18: What is boiling point?
Answer 18: When a liquid is heated. At a certain temperature, a point is reached when the particles have enough energy to break free from the forces of attraction of each other. At this temperature the liquid starts changing into gas. The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
Question 19: Define Sublimation with example?
Answer 19: A change of state directly from solid to gas without changing into liquid state (or vice versa) is called sublimation. Camphor or ammonium chloride directly converted into gas when heated.
Question 20: What do you understand by Evaporation? Write the factor affecting evaporation.
Answer 20: The phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation. The rate of evaporation increases with a) an increase of surface area, b) an increase of temperature, c) a decrease in humidity and d)an increase in wind speed.
Question 21: Why do we feel cool when pour some acetone (nail polish remover) on our palm?
Answer 21: When we pour some acetone (nail polish remover) on our palm, the particles gain energy from our palm or surroundings and evaporate causing the palm to feel cool.