Hello,

If a candidate passes in the additional subject but fails in one of the main subjects, then the candidate will be considered as having passed the examination in such a case.  A language will replace a language only.  For further details the scheme of examinations can be referred to.

Kindly, refer this official Faq link of Cbse for more details:

https://mycbseguide.com/blog/cbse-helpline-frequently-asked-questions/

Hope this will help you!

Thank you!