It is the duty of the several county assessors of the state to correctly describe according to ownership each parcel of real property in the county, and every acre of land or town or city lot must be accounted for on the assessment roll. In instances where real property is exempt from taxation, either under the Arkansas Constitution or because title is vested in the state, this fact must be noted on the assessment roll with the reason for the exemption. The county clerk must likewise in extending taxes account for every parcel of real property within the county.