Dear Intekhab ,

The class 11 and 12 Bihar board are separate exams. Your 12th Bihar board exam will consist of the syllabus that you have in class 12 and your class 11 syllabus will not be considered. So its better that you prepare for your 12th boards from previous year and sample question papers of Bihar board. This will  help you in attending your  exam confidently and also give you a brief idea about the type and pattern of questions asked.

All the best for your future