Page 1 - Lesson Notes
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SAI INTERNATIONAL SCHOOL
                                                     Class - VI
                                              Subject - Chemistry
                                         Topic – Changes Around Us
                        Sub-Topic – Reversible and Irreversible Changes



                                                   Lesson Note
          CLASSIFICATION OF CHANGES:


               A substance undergoes a change to form a new substance, only when certain agents
                 like, heat, light, electricity or force, etc., are applied to it.

               If the agent causing the change is removed, then in some cases, the ‘new substance’
                 undergoes a change in reverse direction to form the ‘original substance’.

               Therefore,  some  changes  can  be  reversed,  whereas,  other  changes  cannot  be
                 reversed.
















          REVERSIBLE CHANGE:

               A reversible change is a change that can be

                 undone or reversed.

               A  reversible  change  might  change  how  a
                 substance looks or feels, but it doesn’t create

                 new substances.
               Temporary changes can be reversed easily to

                 get the original form of the substance.

               E.g., Change of state of matter, Stretching of
                 spring,  Ironing  of  clothes,  rolling  of  roti  from

                 dough,  dissolving  salt  in  water,  Expansion
                 and contraction of metals on heating.




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