Hello sir/ma'am abhi 12th board exam me sirf 2 month rah gye hai to kya mai 2 month me 90+% la sakta hu.
I think you can but not 100% sure.
It's doesn't mean that now you fresh start to studying.. there are only revision or some topic left to read then you can do but you do nothing in whole year and now you want to score 90% then it's been tough tor you..
But you can. For that your hard work and dedication and work in right direction is very necessary.
Good luck.

90+ in board in not that big of a task .
Just stick strictly to the ncert .
First clear your concepts .
Then practice last 10 years papers .
And most importantly believe in yourself .
