Difficulty is very subjective term but I will write as I understand.

• JEE: It require a good understanding of concepts. If you don't know then you can't answer.
• AIEEE and BITSAT: It have few question which can be solved if you know formulas but other would require concepts but these questions are mostly repeated so if you did previous year papers then there is a chance you encounter familiar question.
• State engineering and other private college exams:Pick any formula book, learn all formulas and learn how to use them.

Hey Vandana,

Can you please mention the entrance exam for which you are willing to prepare so that we could give you more accurate answer of yourquery. Now if you are saying for entrance exams related to engineering, mdical or management then you should be get cleared that each examination is difficult one where only top rankers get admission based on merit rank declared after the exams. Hope you find it useful.

Thank you.