The rule that is not a rule for naming binary molecular compounds is: option "c. Identify the oxyanion present and adjust the suffix of this anion to either-ic or -ous."
What is the rule for naming binary molecular compounds?
Rule c is not applicable when naming binary molecular compounds. This rule is related to naming compounds containing polyatomic ions with varying oxidation states, whereas binary molecular compounds consist of nonmetals and do not involve oxyanions.
Rules a, b, and d are standard guidelines for naming binary molecular compounds.
Thus, the answer that is not a rule is: option C.