yes i agree with all of you.solving past 20 yrz paperz is more than enough...yet during last 3 years trend has been changed a bit.............as far as i ve experienced the basic knowledge of science acquired diring tour matriculation and intermediate would help you a lot alongwith solving past paperz ...........so in order to get good marks in EDS follow this strategy and you would expect to score minimum 85 as i am .................extensive reading and concept restructuring is pre-requisite in this regard