Ans: Class 11 Chemistry chapter 7 notes provide a definition of catalyst. It is a chemical that increases the rate of a reaction without changing the reaction itself. Sulphides, oxides, and halides of various metallic and semi-metallic elements, such as aluminium, boron, and silicon, are some of the most prevalent catalysts.  By referring to cbse class 11 chemistry ch 7 notes, students can gain a deeper understanding of catalysis in chemistry.