RBSE Class 7 Science Notes Chapter 6 Physical and Chemical Changes

These comprehensive RBSE Class 7 Science Notes Chapter 6 Physical and Chemical Changes will give a brief overview of all the concepts.

RBSE Class 7 Science Chapter 6 Notes Physical and Chemical Changes

→ Changes can be of two types: physical and chemical.

→ Change in physical properties is called a physical change. It is generally reversible and in such a change, no new substance is formed.

→ Change in which one or more new substances are formed is called a chemical change. All new substances are formed as a result of chemical changes.

→ A chemical change is also called a chemical reaction. Some chemical reactions are :

→ The process of rusting can be represented by the following equation:
Iron (Fe) + Oxygen (O₂, from the air) + water (H₂O) → Rust (Iron oxide, Fe₂O₃)

→ We can prevent rusting by applying a coat of paint or grease. Another way is to deposit a layer of metal like chromium or zinc on iron.

→ Some substances can be obtained in a pure state from their solutions by crystallisation.