Question

Which one of the following orders is not in accordance with the property stated against it?

• A. $F_2 > Cl_2 > Br_2 > I_2$ Oxidising power
• B. $HI > HBr > HCI > HF$ Acidic property in water
• C. $F_2 > Cl_2 > Br_2 > I_2$ Electronegativity
• D. $F_2 > Cl_2 > Br_2 > I_2$ Bond dissociation energy

Answer 1

The Correct Option is D

The question asks about the incorrect order of properties for various halogens. Let's analyze each option based on the given property:

1. F_2 > Cl_2 > Br_2 > I_2 for Oxidizing Power:
   • Fluorine (F_2) is the most powerful oxidizing agent among the halogens because of its high electronegativity and small atomic size, which leads to a strong attraction for electrons.
   • The correct order for oxidizing power is indeed F_2 > Cl_2 > Br_2 > I_2.
2. HI > HBr > HCl > HF for Acidic Property in Water:
   • Hydroiodic acid (HI) is more acidic than hydrobromic (HBr), hydrochloric (HCl), and hydrofluoric (HF) acids because the bond strength decreases from HF to HI, making HI dissociate more easily in water.
   • This order is correct for acid strength in aqueous solutions.
3. F_2 > Cl_2 > Br_2 > I_2 for Electronegativity:
   • Fluorine is the most electronegative element, and electronegativity decreases down the group. Therefore, F_2 > Cl_2 > Br_2 > I_2 is the correct order.
4. F_2 > Cl_2 > Br_2 > I_2 for Bond Dissociation Energy:
   • Bond dissociation energy is the energy required to break a bond. Interestingly, F_2 has a lower bond dissociation energy compared to Cl_2 because of the repulsion between lone pairs of electrons in the small fluorine atoms.
   • The correct order of bond dissociation energy is actually Cl_2 > Br_2 > F_2 > I_2.
   • Thus, the given order F_2 > Cl_2 > Br_2 > I_2 is incorrect for bond dissociation energy.

Therefore, the correct answer is: F_2 > Cl_2 > Br_2 > I_2 Bond dissociation energy, as it does not follow the correct logical order.