PHYSICAL AND CHEMICAL CHANGES
• Those changes in which no new substance is formed are called physical changes.
• During physical changes, the properties of a substance remain the same.
• Many times they are temporary and can be reversed. Melting of ice is one such change.
• There are some changes which are physical but irreversible. For example:
(a) Plucking of leaves
(b) Tearing of paper
(c) Breaking of glass
• Those changes in which a new substance is formed, which have different chemical properties, are called chemical changes.
• Cooking of food, growth in plants and animals, burning of substances are chemical changes as entirely new substances are formed.
• Burning of a candle wax releases carbon dioxide and water vapour (new substances).
Cooking of food:
• On cooking, the colour, hardness and appearance of food changes.
• Cooking of food is a chemical change.
Ripening of fruit:
• Turning of a raw, green mango into a ripe yellow mango is also a chemical change.
Difference between Physical and chemical change: