Final answer:
There are 6 oxygen atoms present in one unit of calcium chlorate.
Step-by-step explanation:
The formula for calcium chlorate is Ca(ClO3)2. To determine the number of oxygen atoms present in one unit of calcium chlorate, we need to multiply the subscript of oxygen by the coefficient of the calcium chlorate in the balanced equation. In this case, there are 6 oxygen atoms in one unit of calcium chlorate. So, there are 6 oxygen atoms present in one unit of calcium chlorate.