Hello Abhishek, 

If your asking for entrance 3xam pattern for bsc agriculture of BHU than there will be 100 question and 25 question will be from chemistry, 25 from mental ability, 50 questions from (zoology+botany) for biology students. OR  (25physics + 25 maths) for mathematics students. OR 50 agriculture questions for agriculture students.

Well if your asking for university syllabus than that you can easily get on bhu official website.

All the best.