I've got 93% in 10th .I've attained A grade in chem,A+ in phy & B+ in maths.But i think iam weak in these sub.what if i take science stream?

With your grading in 10th, I safely say that you are not weak and in fact you are above average. I will encourage you to go ahead with maths, physics, English and Information Practices in your 11th and after 12th, you appear for NDA exam. Any average plus student would pass it. If you succeed, then

If you are weak the you have to go for other field , but i think this is good marks to get admisison in non medical , you can go fro science , if there is you get less marks then there is not a big issue at starting of science at 1th class many students get less marks