Final answer:
To find the oxidation numbers of atoms in a molecule containing three elements, including oxygen and a halogen, you can apply specific rules. Oxygen is typically assigned an oxidation number of -2, hydrogen is usually +1, and halogens like chlorine have an oxidation number of -1, except in certain cases. The sum of the oxidation numbers in a neutral molecule is always zero.
Step-by-step explanation:
The oxidation numbers of atoms in a molecule containing three elements, with one element being oxygen and the other being a halogen, can be determined by following certain rules. In most compounds, oxygen is assigned an oxidation number of -2 and hydrogen is usually +1. Halogens like chlorine (Cl) are assigned an oxidation number of -1, except when combined with oxygen or other halogens. The sum of the oxidation numbers of all the atoms in a neutral molecule must be zero.