Hi pal,
If you are looking for admission in Delhi University ,then you have to secure 90 percent above in your 10th +2  board examination or if you're looking admission in IISC then you have to qualify KVPY examination and for addmission in  JNU you have to qualify the University examination for getting admission in BSC geography.some of other university also gives admission on the basis of 12th marit.
Hope this will help you.
Good luck.