Keeping in mind the age group of the students, the matter has been divided into sections and sub-sections so that the students can learn at their own pace. All new concepts have been developed by class-activity method. Results, wherever possible, have been verified by lab activity method. Objectives questions in the form of Fill in the Blanks, True/False statement and Multiple Choice Questions have been given under the heading ?Mental Maths?. In addition to normal questions, some Higher Order Thinking Skills (HOTS) questions have been given to enhance the analytical thinking of the students. Each Chapter is followed by a Summary which recapitulates the new terms, concepts and results. The last section ?Check Your Progress?, acts as a Unit Test. Model Question Papers have been given at proper places. A new section on Logical Reasoning and Aptitude has been added at the end of the book. A few, relevant case studies have also been added. In entire book, care has been taken to maintain the continuity of the subject matter.