This book has been brought out after taking utmost care and is especially prepared bearing in mind the need of students appearing in all types of competitive examinations (like Railway, SSC, Bank, B.Ed. DSSSB, TGT/PGT, DMRC, Civil Services, NDA/CDS, Nursing, GIC/LIC, FCI, KVS/NVS, etc.) Exams. It may also prove to be highly useful for graduate and postgraduate students of all Indian Universities. It aims at providing the essential principles of Physics, Chemistry and Biology. This book has been formulated as per latest examination pattern, keeping in mind, all competitive examinations and help all types of aspirants. The book has been specially designed to help the students realize their dreams and we hope it will be a helping hand in their path to success.