How does the easing of displacement reactions vary among the halogens?

The correct answer indicates that the ease of displacement reactions decreases down the group of halogens, which reflects how the reactivity of halogens changes with atomic size and electron affinity.

As you move down the group from fluorine to iodine, the atoms become larger due to the addition of electron shells. This increase in size means that the outermost electrons are further from the nucleus and are shielded by inner electrons, making them less tightly held. While fluorine is the most electronegative and has a high tendency to gain an electron, iodine is less so, and therefore, it does not readily displace other halogens from their compounds.

In displacement reactions involving halogens, a more reactive halogen can displace a less reactive one from its compound. Since fluorine is the most reactive, it can easily displace chlorine, bromine, or iodine. Conversely, iodine cannot displace chlorine or bromine from their compounds due to its lower reactivity. Therefore, as you move down the group, the ability of a halogen to displace another in a reaction diminishes, which is consistent with the observation that ease of displacement decreases.

This trend in reactivity is critical in understanding the behavior of halogens in chemical reactions, especially in