Hello KIshan,

There may be situation that some questions may not be there in the ncert book 11 and 12 and if situation arrises that the question was out of syallbus then you should raise the same by challenging the answer keys .If it is out of syllabus you should raise objection of that and if the amount of objections are more in number then definetly NTA would look into this situation and you will get marks.

Hope this helps you.

ALL THE BEST!