Question

Which of the following pairs is not correctly matched?
(A) A halogen which is liquid at room temperature-Bromine
(B) The most electronegative element-Fluorine
(C) The most reactive element-Fluorine
(D) The strongest oxidising agent-Iodine

Answer 1

Hint: Down the group electronegativity of elements decreases and size increases. Thus, an element can easily release outermost electrons going down to the group. In the given options, there are only those elements that belong to group \[{{17}^{th}}\]and that group is called halogen groups.

Complete Step by Step Solution:
In the first option, we need to check if bromine, which is a halogen, is liquid at room temperature or not. Bromine which is the third halogen (group \[{{17}^{th}}\]third element down the group), has less electronegativity as compared to fluorine (first halogen) and chlorine (second halogen). Due to less electronegativity, it is liquid at room temperature but not solid. Thus, this statement is correct.

Next, fluorine , which is the first halogen, has very high electronegativity because of the smallest size of all other halogens and thus tends to attract electrons from less electronegativity elements easily. Thus fluorine is most electronegativity and also very reactive.

Now the oxidising agent is termed as an element that has a tendency to gain electrons from other elements and thus, tends to increase the oxidation state of that other element. But lithium is not a good oxidising agent as its electronegativity is very low and thus has less tendency to attract electrons from another element. So, the last pair is not correct.
Thus, the correct option is D.

Note: Iodine is gaseous at room temperature because of less electronegativity as compared to bromine which is liquid at room temperature. The electronegativity of fluorine is 3.98, electronegativity of chlorine is 3, and electronegativity of bromine and iodine is 2.7 and 2.5.