Hi aspirant,

You got AIR 1689 & your 2nd puc score 50.3. You asked in which iit college you may get.

Now, see, your rank is quite good. Here is a complete list :

1. Textile engg  in IIT Delhi[B.Tech.]
2. Civil, Material Science, Biotech[B.Tech.] and Physics,Earth sciences[B.S.] in IIT Kanpur
3. Production & Industrial Eng., Civil Engineering, Matelargy & Material Science, Biotech Engineering, Polymer Science & Engineering[B.Tech.]; Physics (Dual Degree MSc.), Geophysical Technology(Dual Degree Tech.), Geological Technology (Dual Degree Tech.), Chemistry (Dua degree) in IIT Roorkee
4. Civil Engineering, Manufacturing Science and Engineering, Metallurgical and Materials Engineering, Biotech Engineering, Ocean Engineering and Naval Architecture, Mining Engineering [B.Tech.]; Chemical Engineering at IIT Kharagpur.
5. Aerospace Engineering, Industrial and Systems Engineering, Quality Engineering(Design and Manufacturing), Manufacturing Science and Engineering, Civil Engineering, Biotech Engineering, Mining Engineering, Ocean Engineering and Naval Architecture, Mining Safety Engineering, Agricultural and Food Engineering [B.Tech M.Tech Dual Degree] in IIT Kharagpur.
6. Economics, Physics, Exploration Geophysics, Chemistry, Applied Geology [5yr. M.S.] in IIT Kharagpur.

So, you have good chances.

All the best  !!

:)