Geography Entrance Exam

Yes, I think you are eligible because JNU conducts the admission through entrance mode:
Further details you can get from below given link:
https://www.shiksha.com/humanities-social-sciences/geography/course/m-a-in-geography-jawaharlal-nehru-university-mehrauli-delhi-268822
Its syllabus is almost same as that of undergraduate (honours) in geography. Just go through its syllabus which is available there on internet. Go through the question papers of past years to get an idea what kind of questions will be asked and then start preparing accordingly.
Entrance test consists of 100 marks. 60+40. Where 60 marks are for objective questions of one mark each. Subjective questions are of 40 marks. Practice maps and diagrams to score well.
Hope this helps.

Sri Venkateswara University (SVU) conducts a Common Entrance Test (CET) in order to provide admission to candidates in postgraduate courses offered by its campus and affiliated colleges. Regular (R) and Self-Finance (SF) PG courses (along with their test code and name) in which admissions are done basis SVUCET scores.
SVUCET 2018 Eligibility
In order to fulfill SVUCET 2018 eligibility criteria for Science course admissions, candidates must pass their qualifying exam with at least of 40% marks in the concerned subject. However, exception is for candidates applying for M.Sc Tech in Hydrogeology course. Such candidates should score minimum 50% marks in M.Sc, informs the official website.