Matter
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Any things that occupies space and has a mass is called matter.
Matter can be transparent, translucent or opaque.
For example: book, pencil, water, board, human, wall, air, etc.
Different state of matter
Properties of solid
Solid have fixed shape.
Solid are generally hard.
Solid have fixed volume.
Solid do not flow.
Molecules of solid are closely packed.
Liquid
The matter which no fixed shape but has fixed volume is called liquid.
Properties of liquids
They don’t have fixed shape.
They have fixed volume.
They flow easily.
They cannot be compressed much.
Gas
The matter which has neither
fixed shape nor fixed volume is
called gas.
Properties of gas
Gas do not have fixed volume.
Gas flow very easily.
Gas do not have fixed shape.
Gas can be compressed very easily.
Position of molecules is not fixed.
Classwork
Write any three differences between the following:
Solid and Liquid
Liquid and Gas
Solid and Gas
Density
The density of a substance is defined as mass per unit volume of the substance.
Its SI unit is Kg/m3
Its CGS unit is gm/cm3
Relationship between Density, Mass and Volume.
SI unit of density= Kg/m3
SI unit of Mass = Kg
SI unit of Volume= m3
Relative Density
The ratio of the density of the substance to the density of water at 4°C is called relative density.
It has no unit because it is the ratio of density of two substances.
Differences between density and relative density.
Floating and Sinking
Floating
Sinking
Floating means to be suspend on the surface of liquid.
Sinking means to go down below the surface of liquid.
Floating and sinking of body depends on density.
If a body has less density then density of liquid then it floats.
If a body has more density then density of liquid then it sinks.
Why egg floats on salt water but sinks in fresh water?
Give reasons.
a. Solids do not flow but liquids flow.
Solids do not flow but liquids flow because particles of solid are closely packed but liquid are not.
b. Gas can be compressed easily.
Gas can be compressed easily because molecules in gas are far apart from each other.
c. Relative density has no unit.
Relative density has no unit because it is the ratio of the density of two substances.
d. An egg sinks on fresh water but sinks on concentrated salt solution.
An egg sinks on fresh water but sinks on concentrated salt solution because density of egg is more than fresh water but less than salt solution.
e. Iron nail sink in water but floats on mercury.
=> Iron nail sink in water but floats on mercury because density of iron nail is more than water but less than mercury.
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