Hi,

For IIT preparation you can use the carees360 knockout program. It includes 250+ video lectures, smart study material and mock test also. Of you study strategically and regularly this will help you to improve your rank -

https://learn.careers360.com/knockoutfull-jee-main-april/?icn=jee-main-knockout-lpage&ici=search-section_c360-home

There are many youtube channels also which provide quality videos on these topics. So I will suggest you to read first from books practice the objective then whatever topic you find difficult to understand search for that on you tube to clear the concept.

Hope this helps.