You should focus on ncert books for iit entrance exam. Other than ncert books you may consult following additional books
Mathematics:- RD Sharma and Arihant Books esp of Amit M Agarwal
Physics H. C. Verma
Chemistry
P. Bahadur - Physical Chemistry
Arihant Publications - Organic Chemistry
O.P. Agarwal - IIT Chemistry - for Inorganic Chemistry
All the best
AKASH GOYAL AskiitiansExpert-IITD
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For maths go for TATA MACGRW HILL'S and M.L.KHANNA
For chemistry go for O.P.TANDON[G.R.B PUBLICATIONS] THEY HAVE ALL THREE BOOKS THAT IS FOR PHYSICAL ,ORGANIC,INORGANIC CHEMISTRY and go for ARIHANT PROBLEM SOLVING BOOK.
FOR physics go for ARIHANT and TATA MACGRAW HILL'S.
THESE ARE A FEW BOOKS WHICH I KNOW IS GOOD FOR IIT JEE