Is zakat obligatory on money used to purchase land before the completion of a hawl? Is zakat obligatory on the land itself if it has not been sold due to market stagnation? Is it permissible to delay the zakat on land until it is sold?

As long as you bought the land with the intention of selling it, it becomes a tradable asset subject to zakat (definition) every hawl (lunar year). This hawl is tied to the money with which you bought the land. Therefore, its value should be assessed, and a quarter of a tenth (2.5%) of its value should be given as zakat. If you bought it one month before the hawl of the zakat of the amount [you paid for it], then you must assess its value one month after its purchase and pay its zakat. If you are unable to sell the land, then pay its zakat from the money you possess. Otherwise, it remains a debt upon you, to be paid upon selling the land for every past year.