VITEEE

Yes, he/she can. But one should be thorough with the whole NCERT book. If it is done, then almost the syllabus will be covered. To score better, one can refer additional sources.

Hello Abhirami,
VITEEE is an engineering entrance exam which is for only engineering courses. For integrated M.Sc biotechnology course, there is no entrance exam and the admission is based on board exam marks.

Minimum rank in VIT to get admission should be 90,000 so you can get admission in VIT from the 6th category as well. There are various categories as well with each category admission fees go high. First category closed till 15000 rank and u can get CSE till 9000 rank and IT till 11000 rank but there are 2nd category as well if you want CSE but you have to pay more for that.

VIT has their own system of giving ranks. They give mild weightage to your board marks and whether it's your first attempt or not. Number of questions attempted also have upper hand. Level of paper will be higher than boards but for sure lower than JEE Mains. Some questions may be tricky. Just prepare and try to attempt all questions. Rank upto 9000 will land you with CSE in VIT, Vellore and upto 12,000 in VIT Chennai in first category. Otherwise you can pay more and get in 2nd category.

Not all the NITs are better than VIT.
The starting top 6-7 NIT are definitely better than VIT but if you get to choose between rest of the NITs and VIT choose VIT. Make sure you choose VIT, Vellore and not any other if you also want to enjoy the college life because the placement and all are same for each branch but the campus life you have in Vellore can't be compared to any other campus.
Coming to get a good score, just keep your basics clear the paper for VITEEE is easier than Mains.

If your exam centers is close enough to travel in between gap of these two, then you could manage both the exams simultaneously. If it is not possible, there may be the reason of same timing or distance. You should go for your board examinations. It is more important for you more than anything.

According to my knowledge, if anyone failed to book their slot, VITEEE automatically booked your slot and you will get notified regarding this before 1 week of the exam at least.
All the best.

Yes, you can, if you are going for B.Tech in biotechnology.