willl u plz.tell me on what topic i have to focus for clear that exam.

YOU HAVE TO FOCUS TO CALCULUS, COORDINATE & ALGEBRA MOSTLY IN MATHS FOR CLEARING THE EXAM IIT-JEE.

In maths- coordinate geometry, complex numbers, vectors and probability.. if u want more than include 3d geometry and functions. 

In Chemistry- p-block and coordination compounds, general organic chemistry, isomerism and hydrocarbons(alkanes , alkenes and alkynes), electrochemistry , stoichiometry , solutions , equilibrium and thermodynamics

In physics- Newton laws and friction , electrostatics , current electricity ,magnetic field, electromagnetic induction , heat and thermo (easy scoring topic) , rotational , work and energy