Page 2 - 3-Lesson Note-Reversible and Irreversible Changes
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➢ Let us take an example of Water Cycle as a reversible change.
➢ When the water body is heated by the sun rays, it changes to steam, i.e.,
Evaporation.
➢ The vapourised steam is then condensed to form the clouds, i.e., Condensation.
➢ The water is then released from clouds back to the land surface or water bodies, in
the form of rain, freezing rain, sleet, snow, or hail, i.e., Precipitation.
➢ Thus, water cycles involves a series of repetitive reversible changes forming a cycle.
IRREVERSIBLE CHANGE:
➢ A change which cannot be reversed to form the original substance is called an
irreversible change.
➢ Irreversible changes are permanent changes and cannot be undone.
➢ An irreversible change may also results in the formation of a new substance.
➢ E.g., growth of living things, cooking of food, digestion of food, burning of coal or
paper, ripening of fruits, curding of milk, raw egg to egg omblete, etc.
➢ Mixing and Heating usually brings about irreversible changes
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