Biology teacher

  Chemical Reactions and Enzymes – Easy Line-by-Line Notes (NEET Beginner Level) Chemical reactions and enzymes explained with simple diagrams for CBSE Class 11 Biology students. 1. What is a Chemical Reaction? A chemical reaction is a process in which old chemical bonds break and new bonds are formed . As a result, new substances (products) are produced. Example: Ba(OH)₂ + H₂SO₄ → BaSO₄ + 2H₂O NEET Point: Chemical reaction = Breaking + Formation of bonds . 2. Types of Changes in Chemical Compounds A. Physical Change Only the shape, size, or state changes. No chemical bonds are broken or formed. No new substance is produced. Examples Ice → Water Water → Water vapour Cutting paper Breaking glass Remember: Physical change = No new substance. B. Chemical Change Old bonds break and new bonds form. A new substance is produced. This process is called a chemical reaction . Examples Burning wood Rusting of iron Digestion of food Hydrolysis of starc...