if work out in these 15 days at those chapter i m good at and prepare about 75-80% of the syllabus do i really stand a chance to score around 250 in iit

Dear chirag if u have completed 75-80 % . and u have very confident in these topics then u can easly get 250 marks. but the disadvantage of leaving any topic is that many question in jee requires combination of several chapter to solve that problem. if any part of question requires the knowledge of those topic which u have not prepeared then u can solve that problem. Please feel free to post as many doubts on our discussion forum as you can. If you find any question Difficult to understand - post it here and we will get you the answer and detailed solution very quickly. We are all IITians and here to help you in your IIT JEE preparation. All the best. Regards, Askiitians Experts Badiuddin