M.Sc

Hi Rutuja,
I believe that for admissions into M.Sc. Microbiology, you need to have a B.Sc. Degree in microbiology or a plain B.Sc. Biology. I don't think B.Sc. Hotel management fulfills the eligibility criteria. You must still confirm with what university you want admissions into as it may vary.

In majority of universities, eligibility criteria for M.Sc. Environmental Science is graduation degree in Science (Environmental Science/ Botany/ Zoology / Chemistry / Geology/ Microbiology / Agriculture etc. ). From a recognised university.

I appreciate your interest in pursuing M.Sc. in environmental engineering. To assist you in choosing colleges to pursue the same, kindly refer to the link below for more information:
https://www.shiksha.com/search?q=M.Sc.&sa=^0^100^0^0^0^0^0^0^0^0^0^0^bc:100&rf=filters&ts=463132&sp[]=174&bc[]=100

Yes you can easily take admission in M.Sc. But you have to be a graduate student or qualified graduation.

Following are the entrance exam for M.Sc. :-
1) IIT JAM
2) TIFR GS
3) TMC, Mumbai
4) NEST
5) JEST
https://www.shiksha.com/science/articles/top-bsc-msc-entrance-exams-in-india-blogId-13484

Yes, it is applicable to anyone irrespective of the year of graduation. It is solely dependent on your educational background and what you want to study.