Hello Reshma,

As though there is no such option for changing stream from science to arts for 10+2. This option is only for 10+1. So either you can appear for arts exam papers through other examination conducting boards like NIOS or you can write an application to your principal regarding changing your stream. If your principal does accept your application then you will be able to appear for your choice of stream examination else you'll have to appear for science exam papers only.

Hope this information has cleared your doubt.