This textbook has been designed to meet the needs of B.Sc. Third Semester students of Chemistry as per the UGC Choice Based Credit System (CBCS). With its traditional approach to the subject, this textbook lucidly explains principles of chemistry. Important topics such as solutions, phase equilibrium, conductance, electrochemistry, carboxylic acids, amines, diazonium salts, amino acids, peptides, proteins and carbohydrates are aptly discussed to give an overview of physical and organic chemistry. Laboratory work has also been included to help students achieve solid conceptual understanding and learn experimental procedures.