(i)    Reversible and irreversible changes
    (a)  Reversible  change

    A change which can be reversed by the conditions is called a reversible change. 
    eg. Melting of ice, dissolving of salt in water,  drying of clothes etc.

(b)  Irreversible  change
 A change that cannot be reversed by reversing the condition is called an irreversible change.
 eg. Burning of paper, curdling of milk 

AIM : To find out weather the change can be reversed or not.
                                  Some common changes                 
                           Change             Can be Reversed          

        Raw egg to boiled egg                 Yes/No
        Batter to idli
        Wet clothes to dry clothes
        Woollen yarn to knitted sweater
        Grain to its flour
        Cold milk to hot milk
        Straight string to coil string
        Bud to flower
        Milk to paneer
        Cow dung to biogas
        Stretched rubber band to its normal size
        Solid ice cream to molten
    Some common changes are given in above table. We have to find that the changes given can be reversed or not. 

The answer of changes which can be reversed or not is given in Yes/no in the table below. 

                           Some common changes           
             Change                              Can be Reversed        

        Raw egg to boiled egg                                 No
        Batter to idli                                                 No
        Wet clothes to dry clothes                          Yes
        Woollen yarn to knitted sweater                 Yes
        Grain to its flour                                          No
        Cold milk to hot milk                                   Yes
        Straight string to coil string                         Yes
        Bud to flower                                               No
        Milk to paneer                                             No
        Cow dung to biogas                                    No
        Stretched rubber band to its normal size    Yes
        Solid ice cream to molten                           Yes