Summary of matter in our surroundings class 9
Answers
* Matter is made up of small particles.
* The matter around us exists in three
states ,solid liquid and gas .
*The forces of attraction between the particles are maximum in solids, intermediate in liquids and maximum in gases .
* The spaces in between the constituent particles and kinetic energy of the particles are maximum in the case of solids,i intermediate in liquids and maximum in gases.
* The arrangement of particles is most ordered in the case of solids in the case of liquids layers of particles can slip and slide over each other while for gases, there is no order, particles just move about randomly .
* The states of matter are inter-convertible .The state of matter can be changed by changing temperature or pressure .
* Sublimation is the change of solid state directly to gaseous state with out going through liquid state.
* Deposition is the change of gaseous state directly to solid state with out going through liquids state .
* Boiling is a bulk phenomena. Particles from the bulk of the liquid change into vapour state.
* Evaporation is a surface phenomenon. Particles from the surface gain enough to overcome the forces of attraction present in the liquid and change into the vapour state.
* The rate of evaporation depends upon the surface area exposed to the atmosphere, the temperature, the humidity and the wind speed .
* Evaporation causes cooling.
* Latent heat of vaporization is the heat energy required to change 1kg of a liquid to gas at atmospheric pressure at its boiling point.
*Latent heat of fusion is the amount of heat energy required to change 1kg of solid into liquid at its melting point
* some measureable quantities and their units to remember.
Quantity unit. symbol
temperature. Kelvin. K
Length. meter. m
Mass. kilogram. kg
Weight. newton. N
Volume. cubic. m3
meter
Density. kilogram kgm-3
per cubic meter
Pressure. pascal. pa
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Answer:
Matter is anything that occupies space and had mass.Air,water,sugar,hydrogen and oxygen are few examples.Matter is
made up of very small particles.Particles of matter have space between then and they can attract each other.
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