what marks will be a good means for getting an admission after KEAM exam for those who are appearing with OB caste?
In general, Try to do your best and get basics and solve numericals from each chapter from all the 3 subjects.
try to give mock test and know where you stand and improve your position.
As for marks try to score 80-85% of total marks. A rank in range 2k-3k will make your position secure in 1st tier colleges who accepts KEAM to intake candidates.
Hope it helps!