Can you plz tell me what time does dhuhr and as prayer time expires and becomes a qadha prayer?
Like before maghreb or When?
I usually pray at school but sometimes I miss it so i get home around 4 or sometimes 5 and i pray dhuhr and as then? so is it okay or do i pray qadha?

Asr prayer time is until just before sunset and Zuhr prayer time ends slightly before that. As long as you say both before sunset then it is fine.