Question

Statement I: The covalency of oxygen is generally two but it can exceed up to four. The oxidation state of oxygen in SO₂ is -2 and in OF₂ it is +2.
Statement II: The anomalous behaviour of oxygen when compared to the other elements of group 16 is due to its small size and high electronegativity.
In the light of the above statements, choose the correct answer:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Evaluate the assertions related to the chemistry of Oxygen, its covalency limits, oxidation states in specific compounds, and reasons for its anomalous group behavior.
Step 2: Key Formula or Approach:
1. Oxygen's normal covalency is 2 (e.g., \(\text{H}_2\text{O}\)), but it can rarely reach 4 in specific coordinate complexes (like basic beryllium acetate \(\text{Be}_4\text{O}(\text{O}_2\text{CCH}_3)_6\)).
2. Oxidation states are determined by electronegativity rules. Fluorine is more electronegative than Oxygen.
3. First elements of p-block groups display anomalous behaviors due to lack of d-orbitals, high electronegativity, and small atomic size.
Step 3: Detailed Explanation:
Statement I Analysis:
- Covalency of oxygen is generally 2. However, it can expand its covalency up to 4 in certain complex compounds (e.g., in \(\text{H}_3\text{O}^+\) it is 3, and in \(\text{Be}_4\text{O}(\text{CH}_3\text{COO})_6\) the central oxygen is tetrahedrally bonded to 4 Be atoms).
- In \(\text{SO}_2\), oxygen is more electronegative than sulfur, so it takes an oxidation state of -2.
- In \(\text{OF}_2\), fluorine is the most electronegative element on the periodic table. Fluorine assigns -1. Since neutral, Oxygen must balance with an oxidation state of +2.
Thus, Statement I is entirely True.
Statement II Analysis:
- Oxygen behaves anomalously compared to heavier group 16 elements (Sulfur, Selenium, etc.).
- This deviation is primarily attributed to its exceptionally small atomic size, very high electronegativity, and the absence of vacant d-orbitals in its valence shell.
Thus, Statement II is also True.
Step 4: Final Answer:
Both Statement I and Statement II are true.