JEE

Yes, you can, since your JEE Mains marks are good, and also your marks in class 12th is also good. So, according to me, I think you will be getting that college if opted for.

See, if your JEE score is below 70, then there is very less chance for you to score good marks in the next year. (I am talking about the chances, there can be exceptions but exceptions are very less)
Still, if you know that you won't get any decent college this time and have a decent grasp over the b

You can give Vaishnav entrance exam, SVET, and that way you can take admission in this university. It is a reputed university.

No, it is not compulsory but it is combined entrance exam and conducted by CBSE so it has value all over India by this exam you can take admission in any engineering college of India. That's why it is valued.

COE, Pune
VIT
MIT
Government College of Engineering, Amravati
Sinhgad College of Engineering
D.Y.Patil College of Engineering Akurdi, Pune
Sardar Patel College of Engineering
Government College of Engineering, Aurangabad

Hello Shreya,
Firstly, congrats for your score.
Yes, you can definitely make it up for RCOEM. But, as far as specialization branches are concerned, you need to wait for cap rounds.

It is good, you scored so decent marks in boards. Congratulations for that, But, to get admission in any pursue, you must clear JEE. So, you cannot get admission in any pursue without clearing JEE. But, you can get many good colleges on the basis of your board’s marks. All the best for your future.

No, you won't get selected.

Try to study ncert books from 11th. Solve problems based on applications. Focus on physics mostly. Study hard for 2 years.