| Introduction to chemical reactions | | Chemicals are everywhere, all the substances in the world are chemicals. The rocks, the plants, the animals, all are made up of chemicals. Look around yourself. Rusting of iron objects on exposure to damp air, growth of a child, ripening of a fruit, the changing of milk into curd, the digestion of food in our body are some of the examples of chemical reactions. |  | | When wood burns, heat is released. The end product is ash. This happens because the chemicals in the wood change on heating. The chemicals in the wood change into something different (ash) from wood. | | The air we breathe is a mixture of gases such as oxygen, nitrogen, carbon dioxide and water vapor. These are chemicals. When food is digested in the stomach, the chemicals in the food undergo a series of reactions, to give us energy to live. | | Previous | Next |
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