Question

The property of halogens which is not correctly matched is

• A. \(I > Br > Cl > F\) (density)
• B. \(F > Cl > Br > I \)(ionization enthalpy)
• C. \(F > Cl > Br > I \) (electron gain enthalpy)
• D. \(F > Cl > Br > I \) (electronegativity)

Answer 1

The Correct Option is C

The property of halogens which is not correctly matched is:

\(F > Cl > Br > I \) (electron gain enthalpy)

Explanation:

• Density: Density increases down the group due to increasing atomic mass. Hence, \(I > Br > Cl > F\) is correct.
• Ionization Enthalpy: Ionization enthalpy decreases down the group due to increasing atomic size. Hence, \(F > Cl > Br > I\) is correct.
• Electron Gain Enthalpy: Electron gain enthalpy generally becomes less negative (less exothermic) down the group. However, fluorine has an exceptionally small size. Due to this, there are strong interelectronic repulsions in the relatively compact 2p subshell of fluorine. Consequently, it does not accept the additional electron as readily as chlorine does. Thus, chlorine has a more negative electron gain enthalpy than fluorine. The correct order is \(Cl > F > Br > I\). Therefore, \(F > Cl > Br > I\) is incorrect.
• Electronegativity: Electronegativity decreases down the group due to increasing atomic size. Hence, \(F > Cl > Br > I\) is correct.

Therefore, the incorrect match is:

\(F > Cl > Br > I \) (electron gain enthalpy)

Answer 2

The question asks about the property of halogens which is not correctly matched. Let's analyze the given properties:

Density: The density of halogens increases down the group from fluorine (F) to iodine (I), as shown in the order: \[ I > Br > Cl > F \] Thus, this property is correctly matched.

Ionization Enthalpy: Ionization enthalpy decreases down the group as we move from fluorine to iodine, which is because larger atoms have less hold on their valence electrons. The order is: \[ F > Cl > Br > I \] Thus, this property is correctly matched.

Electron Gain Enthalpy: The electron gain enthalpy becomes less negative as we go down the group. Fluorine has the highest electron gain enthalpy, and iodine has the least. The order is: \[ F > Cl > Br > I \] Thus, this property is correctly matched.

Electronegativity: Electronegativity decreases as we move down the group from fluorine to iodine. The correct order is: \[ F > Cl > Br > I \] Thus, this property is correctly matched.

Conclusion: All the properties are correctly matched, so the question seems to be misleading. The properties listed are all correct according to the expected trends.