respected sir ....i am a student of class 12 giving boards now...i want to ask u should i drop a year for iit or not.... in class 11 i dint studied well and i didnt studied half of class 12th as well. but i completed my syllabus for cbse in 100 days(approx) nd i am hoping to get around 90% in cbse 2015..

Dear student,
Try to give your best shot this time on 4^th of April which is the date for JEE mains. When the results are announced calculate
delta=Qualifying marks – your marks

Now if you think you can achieve this delta if given one year of time then go for one year drop, nothing harm in that. many students do this.

But if your delta is very huge or if you are not that much confident about improving by this much than I would advice not to choose this path because ultimately you will loose out wasting one complete year and all the money and too much hardwork which will make you frustated.
But you second statement that “but i completed my syllabus for cbse in 100 days(approx) nd i am hoping to get around 90% in cbse 2015..“ makes me think that you are very confident and intelligent too because what you have achieved or will be achiving not many can do that . If you are this confident, dont listen to any negative energy which comes towards you and just Go For It.