Is matter around us pure of Class 9


A heterogeneous mixture of insoluble particles of solute, spread throughout a solvent, is called a suspension. The particle size (diameter) in a suspension is more than 10-5 cm. The particles has a tendency to settle down at the bottom of the vessel and can be filtered out, because their size is bigger than the size of the pores of the filter paper.


  •   Milk of magnesia is a suspension of magnesium hydroxide, Mg(OH)2, in water. 
  • Lime water (used for white wash) is a suspension of calcium hydroxide in water. 
  • Paints are suspensions of coloured substances in water or some other liquid. 
  • Bleaching powder in water is also a suspension since bleaching powder is insoluble in water. 
  • The particles of suspension are visible to the naked eye.


  • A suspension is a heterogeneous mixture.
  • The solid particles of a suspension are so large in size (more than 10-5 cm or 10-7 m or 100 nm) that they are visible to the naked eye.
  • The particles of a suspension scatter a beam of light passing through it and makes its path visible (show tyndall effect).
  • The solid particles of a suspension settle down when it is allowed to stand for sometime. In other words, a suspension is unstable.
  • The particles of a suspension cannot pass through a filter paper. Thus, when a suspension is filtered, the solid particles remain as a residue on the filter paper.
  • Suspensions are either opaque or translucent.


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