In the case that the situation was in your control, and you do not have a valid reason as to why you missed your exam, it is highly likely that you will be awarded 0 for that task.
However, some schools are more lenient and it will be up to ur head teacher/principal to decide the next course for action. I know my school is really strict and it will definitely be a zero, but at the end of the day, it is out of your hands what happens next. My advice is to immediately have a conversation with whoever was in charge of the exam, could be head teacher, deputy/principal on what you should do.
If you are extremely lucky, they might have you an estimated rank (based on your previous results), but I've only seen this ever happen to students who had a legitimate excuse (taken to hospital, broken an arm, had covid when it was serious, etc). Or another case is that they ask you to resit the exam, and may or may not change up the questions to ensure no leaks.