Haryana State Board HBSE 9th Class Science Notes Chapter 1 Matter in Our Surroundings Notes.
Haryana Board 9th Class Science Notes Chapter 1 Matter in Our Surroundings
→ Materials found around us have different sizes, shapes and forms.
→ Matter is a substance that possesses mass and occupies space.
→ The ancient philosophers of India have classified matter mainly into five basic elements viz. air, earth, fire, water and sky (which are said to be ‘Panch Tatvas’).
→ The modem scientists have classified matter on the basis of its physical properties and chemical nature.
→ The particles of a matter have presumably sufficient space in them.
→ The purity of honey can be tested merely by pouring down just a drop of it into a glass of water as if honey falls in form of a colour line, then it is supposed to be pure.
→ The particles in the matter do always remain in motion continuously i.e., they do have kinetic energy in them.
→ The kinetic energy of the particles speeds up with the increase in temperature.
→ The particles of matter attract one another, but the capability of force of cohesion is different in every material.
→ Matter exists in three different states namely solid, liquid and gas.
→ Solids are fully incompressible, of definite shapes and fixed volume.
→ The particles of solids have the ability to rotate about accordingly to their mean positions.
→ The solids do not have the property to lose their indentity while intermixing into other solid materials.
→ Liquids are comparatively compressible to solids. They have fixed volume, but no definite shape.
→ Gases diffuse up and dissolve into water. Due to this property of them the aquatic plants and animals sustain life in water.
→ The aquatic living beings are able to breathe in water because of the dissolved oxygen in water.
→ In liquids, there is complete possibility of solubility of solids, liquids and gases.
→ There is comparatively more mixing-rate in liquids than that of solids, since in liquid state the particles have maximum space in them and they can freely move about.
→ In comparison to solids and liquids, gases are more compressible.
→ Due to random speed and maximum space, gases mix up with other gases more quickly.
→ In order to convert the degree of temperature from kelvin into Celsius, 273 should be subtracted from the given temperature and to convert from Celsius into kelvin the given temperature should be added to 273.
→ The melting point of a solid indicates the ability of force of cohesion between its particles.
→ At 0°C, the energy of the particles of water use to be more at the similar temperature than that of the energy of the particles of ice.
→ The boiling point of water is 373 K (100°C).
→ By changing in temperature we can convert matter from one state into another.
→ With the increase in pressure and decrease in temperature, gas can be converted into liquid.
→ Camphor and ammonium chloride are volatile substances.
→ Increase in the level-region, increases the rate of vaporisation.
→ With an increase in temperature, the rate of vaporisation rises.
→ Due to vaporisation, cooling occurs.
→ Diffusion: Intermixing of particles of two different materials by themselves is called diffusion.
→ LPG: By compressing butane at high pressure the fuel-gas used in the kitchen to cook is called Liquefied Petroleum Gas (LPG).
→ CNG: The natural gas after treating it with high pressure and such treated gas which is used in vehicles in the form of fuel is called as Compressed Natural Gas (CNG).
→ Density: The mass per unit volume of a substance is called density. i.e„
Density = \(\frac{\text { Mass of the substance }}{\text { Volume of the substance }}\)
or
D = \(\frac{M}{V}\)
→ Thermometer: The device used to measure temperature is called thermometer.
→ Melting Point: That fixed temperature at which a solid converts into a liquid is called melting point.
→ Melting: The process of melting or changing of a solid into liquid state is known as melting.
→ Dormant (Hidden) Heat of Melting: The heat energy that is required to convert 1 kg of a solid at atmospheric pressure at its melting point into liquid is called dormant heat of melting.
→ Boiling Point: That temperature at a certain atmospheric pressure at which a liquid starts boiling is said to be boiling point.
→ Unexposed Heat of Vaporisation: The amount of heat energy that is required to convert 1 kg of liquid at a certain atmospheric pressure at its boiling point is called as dormant/unexposed heat of vaporisation.
→ Sublimation: The process by means of which a substance converts into gaseous state directly from solid state without changing into liauid is called sublimation.
→ Dry Ice: Solid carbon dioxide is called dry ice.
→ Thawing: Changing of a liquid in solid state is called thawing.
→ Freezing Point: That fixed degree of temperature at which some liquid stmts converting into solid state is called freezing point.
→ Vaporisation: The process where a liquid changes into vapour state below the temperature of its boiling point is called vaporisation.
→ Humidity: The quantity of water vapours present in the air is called humidity.