This book is especially designed for B.Tech. degree students following the guidelines of All India Council for Technical Education (AICTE) syllabus. This book is also useful for B.Sc. chemistry (honours) students. This second edition discusses in detail quantum chemistry and its important applications, MO concept and its applications, aromaticity, comprehensive discussion on UV spectroscopy, NMR spectroscopy as well as IR and microwave spectroscopy, stereochemistry and water chemistry. Besides these, real gas obeying van der Waals equation is also included in this edition. Detailed mathematical approach and well-illustrated figures are also given to understand the basic concept in a lucid manner. Exercises and numerical problems have also been included at the end of each chapter for practice. Appendix is also added which includes a collection of reference tables.