Solid Liquid Gas Part -01





















Highly compressible


Can't flow

Can flow

Can flow

Inter particle forces


Slightly weaker than in solids


Space between the particles


(molecules in a solid are closely packed )

More than that in solid

(molecules in a liquid are less closely packed  )


(molecules in a gas are wide apart )


  • It consist of super energetic and super excited particles.
  • It is a mixture of free electrons and ions.
  • It is the fourth state of matter.
  • It occurs naturally in stars(including sun). The sun and stars glow because of the presence of plasma in them.
  • The fluorescent tubes and neon signs bulbs contain inert gas, when electricity is passed through them , they produce glowing plasma having a characteristic colour.
  • It is the presence of plasma that makes the CFL tube glow.


Bose Einstein condensate –

  • In 1920, Indian physicist Satyendra Nath Bose had done some calculations for a fifth state of matter. Building on his calculations, Albert Einstein predicted a new state of matter – the Bose-Einstein Condensate (BEC).
  • The BEC is formed by cooling a gas of extremely low density, about one-hundred-thousandth the density of normal air, to super low temperatures.

Which of these are solids: Rubber band, Sponge, Salt?

All of them are solids. All of these follow the properties of solids. A rubber band and sponge change their shape only when we apply force on to them. It might appear to you as if salt is taking the shape of the container in which you put it but actually each of its grain has its own definite shape.

Can other matter diffuse into liquids?

  • Yes, other matter can diffuse into liquids whether it is solids, liquids, or gases. This is so because there is a space between the particles of liquid so particles of other matter can slip into those spaces.
  • Diffusing solids into liquids: Mixing sugar in tea
  • Diffusing liquids into liquids: Mixing ink in water
  • Diffusing gases into liquids: The presence of oxygen and carbon dioxide in water

Change of states

  • When a solid is heated , it converted into liquid , when a liquid is heated , it converted into gas.
  • When a gas is cooled it changes into liquid . When a liquid is cooled it changes into solid.
  • The state of substance can be changed by changing temperature or pressure.

Effect of Change of Temperature

  1. Solids:
  • As we heat solids, the kinetic energy between the particles of solids increases which decreases the force of attraction between them and a solid converts into liquid.

Melting point-

         The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point. 

         The melting point of a solid is an indication of the strength of the force of attraction between its particles. 

         The melting point of ice is 273.15 K. 

         The process of melting, that is, change of solid state into liquid state is also known as fusion.

Factors affecting the melting point 

  • For those substances which contract on melting, if pressure increases, Melting point decreases.
  • For those substances which expand on melting, if pressure increases, Melting point increases.
  • The melting point of ice is 0 degree Celsius and the freezing point of water is also the same hence both ice and water exists at this temperature.
  • The temperature point at which solid, liquid and gaseous states may stay together is known as triple point.
  • Melting point will decrease on addition of soluble salts.
  • The use of ordinary salt (sodium chloride) on icy roads in the winter helps to melt ice from the roads by lowering the melting point of the ice.

Fusion – The process of melting of a solid into liquid is called Fusion.