It gives us immense pleasure to present the twelfth edition of GRB New Era Chemistry for Class XI: Part-1, II and Class XII: Part- I, II, the books are designed according to the latest CBSE syllabus. Students will find each chapter enriched with the theoretical explanation along with a variety of questions. The books have been so designed that they contain every necessary tool required for clear understanding and conceptual development on each topic. The summary of the topic along with important points to remember is provided for a quick revision. Conceptual problems are provided in each unit. The books have a wide range of questions to cater to the needs of all students, including brilliant, mediocre, and late bloomers. All questions have been well-graded and written in simple language. The books include NCERT textbook examples and questions with solutions and also very short answer type, short answer type, long answer type questions with answers, and NCERT exemplar problems with solutions. The numerical and examples illustrated for each unit/chapter shall enable students to delve deep to understand better the hidden aspects of the topic. In order to enhance the spectrum of knowledge already acquired by the students, Practice Problems are not only given at the end of each unit but also in between the text wherever required.