CBSE 12th

Hello Rajesh,
You have passed your 12th in 1999 and now you want to do Diploma course in library. Right?
Firstly, let me congratulate you on deciding to study even after so many years of passing out of 12th. I am sure you must be working now hence I suggest you should download brochure cum application form of IGNOU.
You will find plenty of courses that you can do by means of distance education including one about library.

Every college has a minimum criteria of about 55-60%. You can check according to the college you wish to take admission in. The best colleges to study geography in India are:
Madras Christian College, Chennai
Presidency University, Chennai
The Neotie University, Kolkata
Jadavpur University, Kolkata
Queen Mary's college, Chennai
SS Jain Subodh PG College, Jaipur
Lorato College, Kolkata
The IIS University, Kolkata
Nirmala College of women, Coimbatore
Osmania University Hyderabad
OPJS University, Churu
NIMS University, Jaipur

After 12th with PCB there are many options. You can go for MBBS, BDS or any other course.
Other than that, if not interested to become a doctor then you can go with the courses that require biology background like BA/ B.Sc/courses with biotechnology or, B.Ed or other teaching courses with PhD. Apart from these, designing, management, cabin crew, acting, freelancing and many more options are open for students with PCB subjects.

Yes sure you can pursue microbiology

At least, 50% is a must. NATA asks for a minimum of 40% to answer the entrance exam.

Well, there maybe a college like the one you've asked but mostly, in fact in every college, entrance exam is a must. That is another thing if one does't qualifies the entrance and gets admission through donation.

Yes, you can join pharma.D.

Well, Ishaan, 12th standard grades are important but if you are seeking a good job, that too with such a high package, you need to have a graduation degree with a good aggregate. There are jobs for students who are intermediate passed and have no graduation degree but, in these jobs, no such high package is expected or given.

That's a good rank to expect admission in one of the NIFTs, if you are not from the general category.