Is Zakat obligatory on money remaining after purchasing a residential plot of land, knowing that the total value of the money and the land reaches the Nisab, and that the questioner does not own a private home and lives with his family?

Zakat (definition) is not obligatory on money unless it reaches the niṣāb (minimum threshold) and a whole year has passed over it, according to the Prophet's (peace be upon him) saying: "No zakat is due on wealth until a year passes over it." If you buy land for dwelling with a portion of the money before the year passes, and the remaining amount does not reach the niṣāb, then no zakat is due on you for it, as it is below the niṣāb. Similarly, there is no zakat on the land you bought for dwelling.