"Set 2 (N, O, & F) would be more similar in terms of properties.
This is because elements in the same group (column) of the periodic table generally have similar properties due to their similar electron configurations. Fluorine (F) is in Group 17 (the halogens) of the periodic table, and chlorine (Cl) and bromine (Br) are also halogens, which means they have similar properties such as being highly reactive and forming acidic compounds.
Nitrogen (N), oxygen (O), and fluorine (F) are all located in Group 16 (the chalcogens) and Group 17 (the halogens) of the periodic table, respectively. While nitrogen is not a halogen, it is located just above Group 17, and oxygen and fluorine are halogens. Elements in Group 16 and 17 share similar chemical properties such as high electronegativity and the tendency to form covalent bonds.
Therefore, because elements in the same group of the periodic table have similar properties, we would expect Set 2 to be more similar in terms of properties than Set 1. Specifically, nitrogen, oxygen, and fluorine are all nonmetals with relatively high electronegativities and the ability to form strong covalent bonds, which makes them more similar to each other than to the halogens in Set 1" (ChatGPT, 2023)