Question

definition physical and chemical changes

Answer 1

Physical changes are reversible changes which do not change the chemical properties of a substance but change the physical properties 

Chemical changes are irreversible changes which change the chemical and physical properties of a substance with the formation of new products

Answer 2

heya,

physical changes are those changes which occurs physically. they doesn't form a new substance. they are reversible.
for example. ice. when the ice melts it can be water. when we boil the water it becomes streams. 

chemical changes are those change which occurs chemically. they can form a new substance. they are irreversible.
 for example. paper. when we burn paper we get ashes.
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thank you...