Hello candidate,

The pre boards exam are designed in such a way that the appearing students get to have the feel and the the experience of attempting in mock Boards before the real examination begins.

It would be best if you attend all the pre board exams, but if you are unable to attend it because of some certain issues then you can report it to your school authorities regarding your unavailability and it would have no effect on your availability of admit card.

Hope this information helps you!!