hi,

non medical stream means you have mathematics, physics, chemistry in 10+2 course. if you have studied 10th standard exam with mathematics and science then you are eligible to take science stream in 11th standard. your 1 year study in 11th commerce section would not count and it will consider as year gap. however if you have clear understanding of 10th standard mathematics and science then you should not face any issue for studying 11th science stream.

hope it would help.