Dear mehul,

First of all you have to go through the basic text books say NCERT for chemistry,H.C Verma for physics and RD Sharma for maths.

Please refer this site too:  http://www.askiitians.com/iit-study-material/

Please feel free to post as many doubts on our discussion forum as you can.we will get you the answer and detailed  solution very  quickly.

All the best.

Regards,
Askiitians Experts
Sagar Singh