As you have not mentioned which stream you belong to so below I am providing the common scholarship exam which a 12th studying student can apply for -

HDFC Scholarship
G H Raisoni Scholarships For Boys
Padala Charitable Trust Scholarship
Kishore Vaigyanik Protsahan Yojana (KVPY)
Nirankari Scholarship for Meritorious Students
Sitaram Jindal Foundation Scholarship
The Human Welfare Foundation (HWF) Scholarship
Indian Oil Educational Scholarship Scheme etc.

Hope this helps!!!