Hello there it depends on the caste you belong let me consider you are general category, in this case there is very less chance because you will be getting rank under 2000 so less chance is there but you will be getting very good and top nit's. so hope for better all the best.

Hello Suresh

Basically this depends upon ranking and cutoff for the session instead of marks, higher the difficulty level of paper-lesser the marks required to make good ranking. the cutoff ranking for General category falls around 600-650 in cs branch.

However if you will score around 50 or above then there's is higher chances of getting in IITs  for General category students.

But as you stated that you may get 45 so in that case it is quite difficult considering last year's cutoffs.