Hi Lakhan

Improvement exam are given for those subjects in which you are pass but not having good marks.CBSE emprovement exams can be taken in more than one subject.You cannot appear for improvement for those subjects in which you are not pass/or fail.

If you are fail in any of the subjects you have to take compartmental exam conducted by CBSE.Your school can inform you when you have to fill up these forms.

Good Luck