Hello Saanvika Yadav

Yes, you can give BHU LLB Paper for demo. It is up to you whether you want to practice it or not. According to me it is a very good decision to practice the paper to know about the difficulty level of the paper. But you do not need to give the exam along with them. You can arrange the papers online and just practice. Also you might not be knowing some answers.

Hope it helps you.