Hello himanshu,first thing you should know that 75% marks in 12th exam is not enough for getting admission in IIT's ..75%is only one of the basic  requirement for fill the form and to  get admission in NIT's/IIT's..that shit nothing else.

It doesnt matter have you given improvment exam or not .matter is that you must have 75%aggregate(including all 5  subjects) either in first attempt or improvement.

As you are preparing for getting admission in IIT's ,you should do hard labour as much as possible.Thanks

Hi Himanshu Tiwari!

First and foremost important thing to remember is that to get into an IIT you need to have 75% class 12th. If you dont then you are not eligible.

So according to your question, you can give improvement exams in physics, maths, chemistry and then if you get 75%, you are eligible for geeting admission in IIT

But, since you are writing improvements, you need to register yourself for JEE mains exams qualify it and then qualify in JEE advace as you know, JEE mains is valid only for 1 year.

I hope i was able to answer your question!

Good Luck!