Question

Mark the element which can displace the other three halogens from their compounds.
(A) Fluorine
(B) Chlorine
(C) Bromine
(D) Iodine

Answer 1

Hint: All the given elements are halogens. Halogens are very reactive as they contain seven electrons in the valence shell and thus require only one electron to complete their octet. For an element to displace another element, it should have higher reactivity.

Complete Step by Step Solution:
As the order of reactivity of halogens is:
Fluorine > Chlorine > Bromine > Iodine
This means fluorine is the most reactive of all the halogens. The reason for the higher reactivity of fluorine is its small size and higher electronegativity. Hence, fluorine is the element that can displace the other three halogens from their compounds.

Fluorine can displace chlorine from sodium chloride ($NaCl$) to form sodium fluoride ($NaF$).

Similarly, it can displace bromine from sodium bromide ($NaBr$) to form sodium fluoride ($NaF$).

Also, it can displace iodine from sodium iodide ($NaI$) to form sodium fluoride ($NaF$).

Correct Option: (A) Fluorine

Additional Information: Due to the smallest size of fluorine among halogens, its melting and boiling points are very low. Also, the ionisation energy, that is the energy required to remove an electron from the valence shell of fluorine, is very high.

Note: Fluorine (${{F}_{2}}$) and chlorine ($C{{l}_{2}}$) are gases; bromine ($B{{r}_{2}}$) is a liquid; and iodine (${{I}_{2}}$) is a solid. The halogens can form metal halides, hydrogen halides, organohalogens, interhalogen compounds, and polyhalogenated compounds.