Final answer:
Compounds having the same molecular formula but different structural formulas are known as isomers. Resonance structures are different representations of the same compound.
Step-by-step explanation:
Compounds having the same molecular formula but different structural formulas are known as isomers. Resonance structures, on the other hand, are different representations of the same compound. Hence, the pairs of compounds NCO cannot be classified as isomers or resonance structures without additional information.
To determine if they are isomers or resonance structures, we would need to know the full structural formulas of the compounds. Isomers can have different physical and chemical properties, while resonance structures have the same properties and are simply alternative ways of representing the same compound.