For detailed explanation on Some basic concepts of Chemistry, please visit my Unacademy Course at: https://unacademy.com/lesson/introduction-to-the-world-of-chemistry-in-hindi/LG61I71T Basic Concepts of Chemistry, NCERT Exercise Solutions for problem no. 21 to 36. I have also tried to explain the concepts in detaill while applying them in the problems to enable a quick revision for the students. Looking forward to your FEEDBACK :)