Dear pragya,

I wonder how are able to do problems from RD.sharma in 7 th class.If you are that serious read your class books throughly.Understand them propelry.Know how to make your concepts clear,This will hepl you to know how to study new concepts in depth.Science is divided into 2 subjects for JEE physics and chemistry.Do your maths well know,later you will be able to do better in physics and chemistry.

dear pragya ,

                  really it's great thing that u r preparing for iit jee from now . actully u should read ncert books first get clear uer concepts . & i advice u to joind iit prashikshan kedra ,institude for iit the classes also starts from 8th std .it  will benefit u. all the best !!!!!!!!!!!!