- Natural and man-made changes
- Periodic and non-periodic changes
- Desirable and undesirable changes
- Reversible and irreversible changes
- Physical and chemical changes
- Expansion and contraction of materials
- Expansion and contraction of solids
- Expansion and contraction of liquids
- Expansion and contraction of gases
- Applications of expansion and contraction
REVERSIBLE AND IRREVERSIBLE CHANGES
• Changes that occur around us can be broadly categorized as reversible and irreversible depending on whether or not they can be reversed.
• Ice can be changed back to water by melting and the paper boat can be unfolded to get the sheet of paper; so these are reversible changes.
• On the other hand, the fruit cannot be changed back to a flower and the chapatti cannot be changed back to dough; so these changes are irreversible changes.
• Rusting of iron and growth of a plant are examples of irreversible changes.
Read More...REVERSIBLE CHANGES
Reversible Changes:
• Those changes which can be reversed are called reversible changes.
• Reversible changes are temporary.
Examples:
Melting:
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• Melted chocolate can be changed back into solid chocolate by cooling.
• Molten ice cream can be changed back to its solid form.
• Thus, melting is a reversible change.
• Melting of butter and chocolate are also reversible.
Freezing:
Read More...IRREVERSIBLE CHANGES
• Some changes cannot be reversed. These are called irreversible changes.
• Irreversible changes are permanent. For example, an unripe mango is green and sour, but on ripening it usually becomes yellow and sweet.
Ripening of fruits:
• Ripening of fruits is an irreversible change because it is not possible to get unripe fruits from ripened or mature fruits.
Growth of a baby:
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