Is zakat obligatory on commercial land that was purchased ten years ago and has not been offered for sale, with the intention of building apartments and shops on it in the future to sell the apartments and rent out the shops?

If you intend to buy land to build apartments for sale and shops for rent, then either the land is not distinguished between apartments and shops, such as building connected floors (shops below and apartments above). In this case, there is a difference of opinion as to whether it is for trade or for holding (investment), and the more cautious approach is to purify the land with zakat (definition) on trade goods, and it is subject to zakat for one year when sold. The other possibility is that you have distinguished the land between apartments and shops, in which case zakat is due only on the part allocated for apartments.