B.Sc

Both are good options, but according to me industrial chemistry has good scope and placements are good.

It depends in some college, it is necessary, but there are some where it's not necessary. You have to check with individual colleges for that information.

70-90k p.a for BSC PMC Reva University.

Your chances are pretty high as your profile seems very strong. Most probably you'll get an admit for sure. All the best!

Yes, you are eligible for B.Sc Mathematics.

Yes, you are eligible for B.Sc Biotechnology.

https://studyabroad.shiksha.com/canada/be-btech-in-computer-science-engineering-colleges-ds
check out this link. And, also check for eligibility criteria laid out.

Dr S Bhavnagar University has excellent reviews from its present students and alumni. They have very good placements and other facilities as well. I'm not sure which government. College you are talking about. But consider the both in terms of placements and other infrastructure, check which offers better ROI.

You can do a many courses, but the eligibility would be based on many factors, such as country, your marks, IELTS or TOEFL score, experience etc. The popular courses for hotel management graduates are MBA in hospitality, Masters in culinary arts, M.Sc in hospitality or F&B, plethora of PG Diploma programs such as tourism etc.