Dear aspirant !!

Hope you are doing well !

Nothing is Impossible . If you want to do 12th without studying 11th, then you have to be very clear with the concepts of the stream you'd take in 11th. You have to be very clear with all the concepts of 12th. However, it could be difficult for you to get admission in a good school/college.. you can do your class 12 th from up board . First talk to your teachers regarding the same they will guide you more better on this topic .

Thanking you