Page 212 - New Medley 5 Semester 2

e iron nails stuck to the magnet. is is because the substances in a mixture

retain their original properties as they had before they were mixed.

A mixture may contain di erent elements, di erent compounds or both. e

amount of di erent substances in a mixture can vary. A mixture may even
contain two or more solids (soil), two or more liquids (lemon juice in water),
two or more gases (air), solids in liquids (sugar solution, sea water), gases in

liquids (colas have carbon dioxide mixed in sweetened water) and solids in gases
(dust particles in air). us, most things around us are mixtures. We can easily

separate mixtures into their components.

Physical and Chemical Changes

Physical Changes

Break a matchstick. Tear a piece of paper. Stretch a rubber band. What happens?

What happens when a plastic scale gets broken?

e matchstick is still matchstick,
the paper is still paper and the Heating Freezing
rubber band is still rubber band.  

Each piece of scale is still plastic
even though the pieces have Solid → Liquid Liquid → Solid

di erent shapes and sizes. All Ice Water Ice again
these are physical changes. What Melting of ice and freezing of water are physical changes.

happens if you leave an ice cube in open? It melts into water and when water
is frozen, it becomes ice again. If you boil water, it vaporises into steam. If this

steam is allowed to come in contact with a cold surface like a steel plate, it
condenses back into water. us, on heating or freezing water, its composition

does not change but its physical state changes. Such changes in which substances
do not change their composition but change their physical state are called physical

changes.

Formation of dew drops by condensation of Knowledge Zone
atmospheric water vapour is also an example Mixing of salt in ice lowers its melting

of physical change. point. This interesting fact is used by
the ice cream vendors to sell out the
us, physical change is a: firmly frozen ice creams to you all, even

 temporary and reversible change. without an electric refrigerator.

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