suggest some good practice books.

hey,

Physics:

H.C.Verma, it is the best book for physics, which will definitly not even strong your theortical concepts but also have very good collection of question

I.E.Irodov, good book with dificult questions

Chemistry:

J.D.Lee

Morrison & Boyd

O.P.Tandon

Maths:

Arihant

TMH

for more books you can visit this link

http://www.askiitians.com/Important-books-iit-jee.aspx