how can I become a government teacher for class 11 ,12 with chemistry
You can definitely become a government teacher for classes 11th and 12th in chemistry, but for that, you will have to complete some degrees such as B.Ed. You ought to complete b.ed with minimum 55% marks from a recognised University. You may also complete degrees like TGT, PGT etc., And then, sit for CTET or NCTE examination, clear it to get recruitment.
Hope this helps.
Good luck!