Here's how to determine it:

* Atomicity refers to the total number of atoms present in a molecule.

* KClO3 represents the chemical formula for potassium chlorate.

* The formula shows one potassium atom (K), one chlorine atom (Cl), and three oxygen atoms (O).

* Therefore, the total number of atoms in KClO3 is 1 + 1 + 3 = 5.