# NCERT CLASS IX - Science Textbook Chapter 1 - Matter in Our Surroundings The mass per unit volume of a substance is called density (density = mass/volume). Arrange the following in order of increasing density - air, exhaust from chimney, honey, water, chalk, cotton, and iron. (a) Tabulate the differences in the characteristics of states of matter. (b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy, and density.

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by amitVala120

2015-05-16T18:23:47+05:30

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Increasing order of density
cotton,  air,  exhaust from chimney, chalk, water, honey, iron
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Matter is some thing that occupies space and has a mass.

states of matter:
solid, liquid, and gas.

solid has a definite shape, volume, mass.  It is seen and has colors.  Solids have a smell.    They have a density.  They are rigid.  They are not easily compressible.  But some solids like cotton are compressible.  Some solids like iron are very hard to compress.   They are not fluid - they do not flow.  Particles in solids in general do not have kinetic energy which is visible.  They remain at rest.

Liquid does not have its own shape.  It occupies the shape of the container.  Liquid spreads and flows on a planar surface.  Liquids are viscous ie., they are sticky.    Liquids have color, smell.  Liquids have mass and volume.  They have a density.   Liquids are not rigid.  They are fluids - they flow.  They are not easily compressible.  They do not fill an entire container.  They only fill as much as the volume allows.  Liquids when not flowing, do not have any visible kinetic energy.

Gases do not have a specific volume.  They occupy the entire container they are in.  Gases are generally not visible.  But some fumes/ gases are visible in colors, but not the matter of the gases.
Gases do not have a definite density.  Some gases have odors and some do not have.  Gases are not rigid.  They are fluids - they flow.  They have no shape of their own.  The particles of a gas have kinetic energy - the particles are constantly traveling at high speeds.

Particles in Gases have more kinetic energy than liquids and,  particles in liquids have more kinetic energy than solids.

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