Final answer:
Naphthalene is known to sublime when heated, it is a solid that can transition directly to a gas phase without becoming a liquid first. The correct answer to the sublimation question is option 'III only (naphthalene)'.
Step-by-step explanation:
The question at hand is asking which of the listed substances will sublime when heated. Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.
Out of the options provided, naphthalene is known to undergo sublimation upon being heated. Substances that have relatively weak intermolecular forces are more likely to sublime. Naphthalene, which is a white crystalline solid with a characteristic odor is often used in mothballs and it sublimates easily, meaning naphthalene's vapor pressure is sufficient at ordinary temperatures for it to slowly change from a solid state directly into a gaseous state.
In contrast, carbon monoxide does not sublime but rather melts and then evaporates upon heating. Therefore, the correct answer to which substance sublimes when heated is III only (naphthalene).