Each molecule of K3PO4 contains three atoms of potassium, as indicated by the subscript 3 in the chemical formula of the compound.
The question asks about the number of potassium atoms in the compound K3PO4. This is a straightforward stoichiometry question where the subscript in the chemical formula indicates the number of atoms of each element present in one molecule of the compound. Since the subscript for potassium (K) in K3PO4 is 3, there are three potassium atoms in each molecule of K3PO4.
In conclusion, there are three atoms of potassium in one formula unit of K3PO4, which matches the subscript preceding the K in the chemical formula.