class 7 chemistry (English Medium)

Class 7 Chemistry – CHAPTER 5 : PHYSICAL AND CHEMICAL CHANGES

Physical and Chemical Changes There are two types of changes, physical and chemical changes. Physical Changes Example: Melting of ice and freezing of water. Examples of physical change: Definition of Chemical Change Chemical change is a permanent change which cannot be reversed and in which the chemical properties of a substance change with the change […]

Class 7 Chemistry – CHAPTER 4 : ACIDS,BASES AND SALTS

Acids, Bases and Salts Chemicals can be broadly classified into three categories, acids, bases and salts. Acids Examples: Hydrochloric acid and sulphuric acid are corrosive acids. Carbonic acid is a non-corrosive acid. Organic acids: Naturally occurring acids obtained from plants and animals. Mineral acids: They are obtained from minerals present in the Earth’s crust. Bases

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