The present edition has been thoroughly revised to make the book more useful and comprehensive. Chapters have been rearranged and solved examples have been added, where ever felt necessary, for easy understanding of the subject matter. A number of chapter such as Nomenclature of Organic Compounds , Stereochemistry , States of Matter , Phase Rule Lubrication and Lubricants etc. have been rewritten. Chapters on Petroleum and Petrochemicals and Instrumental Methods of Analysis have been added in this edition. Further, most of the chapters have been reinforced with additional materials wherever considered necessary. Suggestions for the improvement of the book will be gratefully acknowledged. Author is thankful to the publisher for taking keen interest in bringing out this edition in time.