Question

Which one of the following correctly represents the order of stability of oxides, \( X_2O \); (X = halogen) ?

• A. \( \text{I}>\text{Cl}>\text{Br} \)
• B. \( \text{Cl}>\text{I}>\text{Br} \)
• C. \( \text{Br}>\text{Cl}>\text{I} \)
• D. \( \text{Br}>\text{I}>\text{Cl} \)

Hint:

A useful mnemonic to remember the "middle-element anomaly" in the p-block: Bromine often has lower stability in its compounds (like oxides or oxyacids) compared to its neighbors Chlorine and Iodine.

Answer 1

The Correct Option is A

The question requires us to determine the order of stability of the oxides of halogens, denoted as \(X_2O\), where \(X\) is a halogen (Iodine, Chlorine, or Bromine). To solve this, we must consider the nature of the oxides and the underlying factors that influence their stability.

1. Understanding the Oxides:
   • Halogens form oxides in different oxidation states, and the stability of these oxides depends on their ability to form stable structures with oxygen.
2. Factors Affecting Stability:
   • The stability of halogen oxides can be influenced by factors such as the bond strength between the halogen and oxygen, and the size of the halogen atom.
   • Larger halogen atoms tend to form less stable oxides due to the weaker bond strength and the steric effects.
3. Order of Stability:
   • Iodine, being the largest halogen among the three, forms the most stable oxides, followed by chlorine, and then bromine.
   • This order is explained by the fact that iodine forms stronger bonds with oxygen due to its larger atomic size leading to more dispersed electron clouds which helps in stabilizing the oxides.
4. Correct Answer:
   • The correct order of stability for the oxides \(X_2O\) is \( \text{I} > \text{Cl} > \text{Br} \).
5. Elimination of Other Options:
   • \( \text{Cl} > \text{I} > \text{Br} \): Incorrect because iodine oxides are more stable than chlorine oxides.
   • \( \text{Br} > \text{Cl} > \text{I} \): Incorrect as bromine oxides are less stable than both chlorine and iodine oxides.
   • \( \text{Br} > \text{I} > \text{Cl} \): Incorrect since bromine oxides are least stable.

Hence, the order \( \text{I} > \text{Cl} > \text{Br} \) correctly represents the order of stability of halogen oxides \(X_2O\).