Well, this is a very frequently asked question and most studnts op for onlin studies as textbooks are boring . In this regard , the best websie to refer is hscboards.wikia.com .
This site is free of cost to use . You can read articles and chapter wise explanations , important questions , Revision Notes and much more . They also give good motivational artcles on their site . It is a must try .
All the best for your exams !
Prepare withHSC Boards Wiki !