ATAR estimate and you're doing preliminary? Ok, I will do a random assumption that you are actually in Year 12. From those ranks you certainly will be doing relatively well. Most likely an ATAR around 94+
If you are really in year 12, don't drop any of the subjects. But if you are in Year 11, why did you ask about ATAR?
But anyways, if you want to drop something make sure you don't like it. But if you ask me I would say drop Chemistry. I would assume you are French so yeah
keep that one.