Question

Chlorine cannot displace
(A) Fluorine from NaF
(B) Iodine from NaI
(C) Bromine from NaBr
(D) None of these

Answer 1

Hint: In a displacement reaction one element in a reaction tends to displace another element if it is more reactive than that another element otherwise it cannot displace another element.

Complete Step by Step Answer:
Chlorine which is a halogen with an atomic number of 17, will displace the element which is less reactive than it. If any element which is more reactive than chlorine, is present in the reaction then chlorine cannot displace that element.

In the given option, molecules that will react with one molecule of chlorine are NaF, NaI, and NaBr. As we can notice that chlorine, fluorine, iodine, and bromine all belong to the halogen group which is group\[{{17}^{th}}\]. Now as we move down the group reactivity of elements decreases.

Reactivity has depended on the tendency to make bonds with another atom to complete an octet. And this tendency is greater for the more electronegative element. Fluorine, which is the first element of the halogen group, has more electronegativity than other halogens. So chlorine cannot displace fluorine from NaF as fluorine is the most electronegativity and reactive halogen in group \[{{17}^{th}}\] (chlorine is also a halogen) such as
\[C{{l}_{2}}+\text{ }NaF\text{ }\to \text{ }No\text{ }reaction\text{ }will\text{ }occur\]
Thus, the correct option is A.

Note: Chlorine can displace bromine and iodine as both are below the chlorine atom going down the group \[{{17}^{th}}\]. Thus, bromine and iodine are less reactive because of their large size (thus, cannot form a stronger bond with Na) and thus, chlorine can displace bromine from NaBr and iodine from NaI.