Hard and Soft Acids and Bases (HSAB) is a chemical theory developed by Ralph Pearson that classifies chemical species as either "hard" or "soft", and either acids or bases, depending on their size and polarizability. The theory states that hard acids prefer to bind to hard bases and soft acids prefer to bind to soft bases. The document is a thank you note from Dr. Geeta Tewari in the Department of Chemistry at D. S. B. Campus of Kumaun University in Nainital.

1. Hard and Soft Acids and Bases (HSAB)
Dr. Geeta Tewari
Associate Professor
Department of Chemistry
D. S. B. Campus, Kumaun University, Nainital

25. Thank You