Hello Raj!

Solving question papers before board exams will really help you a lot. You will be able to understand the pattern of questions, in some cases you can even predict the questions. Solving numerous question papers will also help you gain speed. And this speed is going to get you good percentage. Maintaining speed and presence of mind is all what is required to crack any exam. 

If you are looking for question papers offline, then there are several books that provide previous year question papers as well as sample question papers. There are many good publishers such as Evergreen, Arihant, Oswal etc. 

There are many many more books available in Amazon, flipkart etc. So you can order from there. Or simply you can visit a book store near you.

If you are looking for question paper in PDF format or an ebook, this is also a good option. So you can visit the website www.ncerthelp.com where you can get access to wide range of study materials and ebooks.

Here you can download previous year question paper for any subject and any class. Just go through all these and attempt the question papers like you are giving your final exam.

Best of luck for your exam.

Thank You!