Volume 4 is the fourth of the volume series on physical Chemistry written by Dr. K L Kapoor. This book is useful for 4th and 5th semester students of B.Sc Chemistry (Hons and Gen). updated sixth edition on quantum Chemistry and molecular spectroscopy is divided into 5 chapters and focuses on Atomic Structure, Chemical Bonding, electrical and magnetic properties, molecular spectroscopy and its applications. Iupac recommendations along with SI units have been incorporated in this book. The revised edition includes probability of finding Harmonic oscillator in classical forbidden region; commutator of xn and PM; e-type and br-type of delayed fluorescence; and jablonski diagram to display electronic transitions in a molecule. Strictly in accordance with latest IUPAC recommendations and SI units being adopted throughout the text\n\nComprehensive coverage of wave mechanics, energy quantization and Atomic Structure, theories of Covalent bond, electrical and magnetic properties of molecules, molecular spectroscopy, molecular Symmetry and its applications\n\nPerfect blend of both theoretical and application-based concepts\n\nExtensive chapter-end numerical including revisionary problems, try yourself problems and numerical problems