NCERT Solutions Class 9th Science Chapter – 1 Matter in Our Surroundings
| Textbook | NCERT |
| Class | 9th |
| Subject | Science |
| Chapter | 1st |
| Chapter Name | Matter in Our Surroundings |
| Category | Class 9th Science |
| Medium | English |
| Source | Last Doubt |
| NCERT Solutions Class 9th Science Chapter – 1 Matter in Our Surroundings Notes In this Chapter We Will read about Matter in Our Surroundings, States of Matter, Solid, Liquid, Gas, Matter, Effect of temperature, Melting point, Boiling point, Latent heat of fusion, Latent heat of vaporization, Freezing, Condensation, Evaporation, Sublimation, Factors affecting evaporation and More much. you have provided easy notes which use in your study make progress in education. |
NCERT Solutions Class 9th Science Chapter – 1 Matter in Our Surroundings
Chapter – 1
Matter in Our Surroundings
Notes
Matter
| The matter is the material of which everything in this universe, (in and around us) is made up of. It is anything that occupies space and has mass and offers resistance to any applied force. |
Physical Nature of Particles
| Matter is made up of particles. The particles of matter are very-very small. |
Characteristics of Particles
| Particles of matter are continuously moving Particles of matter have space between them Particles of matter attract each other |
(i) Particles of matter are continuously moving
| they possess kinetic energy. As the temperature rises, particles moves faster because kinetic energy of the particles increases. |
(ii) Particles of matter have space between them
| When we make tea, coffee or lemonade (nimbu pani), particles of one type of matter get into the space between particles of the other. This shows that there is enough space between particles of matter. |
(iii) Particles of matter attract each other
| When we open a water tap, try to break the stream of water with out fingers, can we do this? No, because the stream of water remains together. Particles of water are held together because of the force of attraction between them. |
States of Matter
| There are three states of matter: solid, liquid and gas. |
Solid
| A solid is that state of matter which has a fixed shape, fixed mass and fixed volume. For example – Rock, Wood, Copper, Ice, etc. |
Liquid
| A liquid which have No fixed shape and Fixed volume are called liquids. For example – milk, water, petrol, kerosene, alcohol, oil, etc. Since liquid can flow, it is also called fluid. |
Gas
| Gases have neither a fixed volume nor a fixed shape. The gaseous state has the highest compressibility as compared to solids and liquids. The rate is diffusion is higher than solids and liquids. |
Change of State of Matter
| Water can exist in three states of matter i.e., solid – ice, liquid – water, gas – water vapour. On heating ice melts into water and then converts into water vapours. |
Melting point
| The temperature at which a solid melts to form liquid at the atmospheric pressure is called its melting point. Melting point of ice is 273.16 k (0oC). |
Latent heat of fusion
| The amount of heat required to change 1 kg of solid into liquid state (at its melting point) at atmospheric pressure is called the latent heat of fusion of the solid. |
Boiling point
| The temperature at which a liquid boils to form vapour at the atmospheric pressure is known as boiling point. Boiling point of water is 373 k (100oC + 273 = 373 k). |
Latent heat of vaporization
| The amount of heat required to change 1 kg of liquid into gaseous state (at its boiling point) at atmospheric pressure is called the latent heat of vaporization of the liquid. |
| We can change one state of matter to another state by changing temperature At 25°C, Water is liquid. At 0°C, Water is solid (ice) as well as liquid. At 100°C, water is gaseous state (steam). |
Sublimation
| The change of solid directly into vapours on heating and of vapours into solid on cooling without passing through the intervening liquid state is called sublimation. Example: When camphor or ammonium chloride is heated in a China dish covered by a inverted funnel (with cotton plug in its upper open end), the vapours of ammonium chloride are converted into solid ammonium chloride on coming in contact with the cold inner walls of the funnel. |
Effect of Change of Pressure
| If we compress a gas in a cylinder, the distance between the particles of gas is reduced and finally gas is liquefied on lowering temperature. By applying high pressure, the particles of a gas can be brought close together. Solid carbon dioxide (dry ice) is changed into carbon dioxide gas directly without changing into liquid when pressure is reduced to one atmospheric pressure. Thus, states of matter Le., solid, liquid and gas are determined by temperature & pressure. |
Evaporation
| A surface phenomenon in which liquid changes into vapours at any temperature below its boiling point is called evaporation. Particles on the surface of a liquid have higher kinetic energy than others, so they break the forces of attraction between the particles & escape from the surface of liquid in the form of vapours. |
Factors affecting evaporation
| Rate of evaporation depend on (a) Exposed surface area – On increase surface area of liquid, rate of evaporation increases. (b) Increase in temperature – Increase kinetic energy of particles hence rate of evaporation increase. (c) Humidity – When the humidity of air is low, evaporation rate is increased. More humidity, less evaporation. (d) Wind – When wind speed increases, rate of evaporation also increases. |
Evaporation always causes cooling
| The cooling caused by evaporation is based on the fact that when a liquid evaporates, it takes latent heat of vaporization from surrounding which on losing heat get cooled. Examples – (i) When we put acetone on our hand, it gets vapourized by taking heat from our hand and our hand feels cool. (ii) We should wear cotton clothes in summer to keep us cool and comfortable as cotton is good absorber of water, so it absorbs the sweat from our body and exposes it to air for evaporation of sweat thus cools our body. (iii) Often people sprinkle water on ground during summer. This water takes heat from ground and surrounding air to evaporate, thus making the place cool. |
Effect of temperature
| On increasing the heat, the particles gain energy and start vibrating with greater energy. Due to increased kinetic energy the particles overcome the force of attraction and a new state is obtained. |
Effect of change of pressure on the matter
| On applying pressure, the particles of matter can be brought close together and the state of matter can be changed. For example, CO2 gas can be solidified by applying pressure and lowering temperature. |
Freezing
| The change in the liquid to the solid phase at a constant temperature is called freezing. |
Condensation
| Condensation is the process through which the physical state of matter changes from the gaseous phase into the liquid phase is called Condensation. |
Question 1. What is diffusion?
The intermingling of molecules of one substance with that of the other is called diffusion.
Question 2. Give the temperature at which water exists in two different phases/states.
At 0°C water can be in solid or in liquid state.
At 100°C water can be in liquid or in gaseous state.
At 100°C water can be in liquid or in gaseous state.
Question 3. What is Kelvin?
Kelvin is the SI unit of temperature (0°C = 273 K).
Question 4. Give two examples of diffusion.
Milk drops dissolved in water and perfume sprayed in a room.
Question 5. Name the state of matter that have the tendency to maintain their shape when subjected to outside force.
Solid
Question 6. What is dry ice?
Solid carbon dioxide obtained by cooling and applying pressure on carbon dioxide gas. It does not melt so it is called dry ice.
Question 7. What is humidity?
The air holds water vapour, this air with water is called humid air and the phenomenon is called humidity.
Question 8. Give two properties of solid.
(1) Solids have fixed shape and are rigid. (2) Solids cannot be compressed.
Question 9. dame any three substances that show sublimation.
Ammonium chloride, camphor and naphthalene balls.
Question 10. What is normal atmospheric pressure?
The atmospheric pressure at sea level is 1 atmosphere and taken as the normal atmospheric pressure.
You Can Join Our Social Account
| Youtube | Click here |
| Click here | |
| Click here | |
| Click here | |
| Click here | |
| Telegram | Click here |
| Website | Click here |