Is zakat obligatory upon a non-working female student, and how is it calculated if the money is deposited in the bank from different sources and a portion of it has been withdrawn?

Whoever's wealth has reached the نصاب (minimum threshold) and a Ḥawl (full lunar year) has passed on it, must pay zakat, even if they are unemployed. It is obligatory to hasten in paying the zakat for past years in which the conditions for zakat were met, while striving and being cautious in determining the number of years and the amount of wealth to be zakat-ed to clear one's conscience, in accordance with His (the Almighty's) saying: (Allah does not burden a soul beyond its capacity).