M.Sc Eligibility

https://www.shiksha.com/animation/2d-3d-animation/course/m-sc-in-visual-communication-loyola-college-lc-chennai-nungambakkam-109010
Please go to the link that I am sharing here to know about this.
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Yes, you are eligible to pursue M.Sc in Information Technology in Hindustan College of Arts and Science.

Dear, As mentioned by you - Information security and Cyber Forensics course is under Department of computer Science and Engineering is a post graduate programme offered by Dr. M. G. R. Educational and Research Institute eligibility of which is B.E/ B.Tech (CSE, ECE, EEE, IT), /M.Sc. CS IT) /M. CA. So, after completion of your MCA you can pursue for the same. Best wishes.

Yes, you can apply for M.Sc in food and nutrition. For more details information you can see below link:-
https://www.shiksha.com/science/course/amp/m-sc-in-food-and-nutrition-the-maharaja-sayajirao-university-of-baroda-vadodara-179150.
Hope this helps you.
Thanks!

Eligibility for M.Sc. Environmental Science-
As a minimum criterion of eligibility, aspiring candidates need to have completed:
Higher and Senior Secondary levels of education (classes X and XII) with a minimum aggregate score of 60%.
Graduation in Science/ Engineering/ Economics/ Mathematics/ Statistics/ Geology/ Geography, with a minimum aggregate score of 60%.
Often candidates are required to qualify an institute, state or national-level entrance test for admission to the course.

Please check for your eligibility to pursue a course in M.Sc. In forensic Science and criminology from the criteria mentioned below:
Eligibility for M.Sc. In Forensic Sciences
Minimum eligibility criteria for M.Sc. In Forensic Science course may vary across institutes. Primarily, the criteria include:
Bachelors degree in Science/ engineering / pharmacy/ medicine, obtained from a recognised university. A minimum aggregate score of 60% at the level of graduation. Regards.

Well, it affects during placements. Some companies (very few) would specifically ask for candidates who had no history of arrears. But, many would just allow candidate with one backlog but has cleared it at present. Thus, it is always best to clear it, by third year and get no backlogs in last two years. You might lose few companies. But, if you have already had one, then clear it and move on. Don't lose any hope. But once you pass out and are no longer a fresher, it won't affect much. However, study as if you want no backlogs, who knows you might lose your dream company because of one mistake you made.

Yes, you can do it without any doubt. It will be easier for you as you already a computer Science graduate.
NIT (s) ask for maths as a subject in your 10+2 or graduation level. Rest, there are many universities which doesn't even consider Maths as a criteria.