Question

For which one of the following properties of halogens the sequence F > Cl > Br > I holds good?
A. Electron affinity
B. Electronegativity
C. Atomic Radius
D. Boiling Point

Answer 1

Hint: In this question, we are given the order and we have to answer which option follows this order. For this first we must know about the properties. Let us discuss the properties to answer this question.

Complete Step by Step Solution:
We know group 17 are referred as halogens and are known as halogen groups. This group consists of fluorine, chlorine, bromine, iodine and a radioactive element astatine.

Let us discuss the properties of the halogen family:
Electron Affinity: It is defined as the amount of energy released when an electron is added to an atom to form a negatively charged ion. So the electron affinity goes on increasing as we move down the group because of decrease in size. F has low electron affinity the Cl but higher than Br because of the small size of F.
So the order is Cl > F > Br > I.

Electronegativity: It is the tendency of an atom to attract the pair of electrons towards itself. As we go down the group, size of the atom goes on increasing and hence electronegativity goes on decreasing.
So the order of electronegativity in halogens is F > Cl > Br > I .

Atomic Radius: It is simply the size of an atom. We know as we move down the group, the number of protons and neutrons increases and thus the atomic radius goes on increasing.
So the order of atomic radius in halogens is I > Br > Cl > F.

Boiling Point: We know the halogens exist as non- polar, diatomic molecules that increase with the increase in size as we go down the group. So the boiling point also increases when we move down the group.
So the order of boiling point is I > Br > Cl > F.

As we see, only electronegativity follows the order F > Cl > Br > I .
Thus, Option (B) is correct.

Note: In this type of questions, students must have the deep knowledge of increasing or decreasing the properties of halogens and the reason behind them being able to give the correct answer.