Would fluorine's chemical properties resemble those of oxygen or those of chlorine?

chlorine

Explanation:

In the periodic table, elements are placed together in the same group, because of their same chemical and physical properties.

Fluorine is placed in group 17,

Oxygen is placed in group 16.

And,

Chlorine is placed in group 17.

Therefore, The chemical properties of fluorine resembles the most with Chlorine, rather than oxygen,

Because as shown above, the Fluorine and Chlorine are placed in common group number 17.