What to study on d day before exam

A student can divide the syllabus into two parts - One with which he/she is reasonably comfortable and the other which is difficult (u keep getting confused). You should have identified these areas during your course of preparation for exams. 

The day before exams should be dedicated, in my opinion, to the tougher parts. You can deal with the simpler chapters with your earlier preparations and revisions. For practical subjects, mark specific problems/adjustments which appear to be tricky, difficult and have a glance on the day of exam.