How to crack upsc cse from chemistry as an optional ...1-start reading basics of subject alongwith previous year question paper 2-match syllabus and then eliminate extra topic from your textbook (Like carbohydrate not include in ias)3- solve 5 question daily basis and evaluate your answer from others copy answer.6-for polymer chemistry i think read only and only ncert class 12 chemistry because question comes from direct ncert lines to line.7 for organic chemistry use multiple resources like reaction mechanism used peter sykes )8-and same strategy for physical and inorganic .by Dharmendra yadav aiims rank 373.