Question

Observe the following sets: 

Which of the above sets are correctly matched?

• A. \( {i, ii, iv only} \)
• B. \( {i, iii only} \)
• C. \( {ii, iii, iv only} \)
• D. \( {i, iii, iv only} \)

Hint:

For properties like bond order and dipole moment, remember to apply the molecular orbital theory and the structure of molecules to determine the correct order.

Answer 1

The Correct Option is C

We are given several orders and their corresponding properties. Let us check the correctness of each order and property:
- Order i: NH₃>H₂O>SO₂ (Bond angle): The bond angle in NH₃ (107.5°) is greater than that in H₂O (104.5°), which in turn is greater than SO₂ (119.5°). So, this match is correct.
- Order ii: H₂O>NH₃>HS⁻ (Dipole moment): H₂O has the highest dipole moment, followed by NH₃, and HS⁻ has the lowest dipole moment. Thus, this match is correct.
- Order iii: N₂>O₂>H₂ (Bond enthalpy): N₂ has the highest bond enthalpy due to its strong triple bond, followed by O₂, and then H₂ with the lowest bond enthalpy. This match is correct.
- Order iv: NO⁺>O₂⁺ (Bond order): NO⁺ has a higher bond order compared to O₂⁺, as indicated by molecular orbital theory. Hence, this match is correct.
Thus, the correct answer is \( {ii, iii, iv only} \).

Answer 2

Analyzing the Given Orders and Their Corresponding Properties:

🔹 Order i: NH₃ > H₂O > SO₂ (Bond angle)
- ❌ This order is incorrect. The bond angle in SO₂ is approximately **119.5°** due to its sp² hybridization and trigonal planar structure. In contrast, NH₃ (107.5°) and H₂O (104.5°) have smaller bond angles due to lone pair repulsions on the central atom (N and O respectively). Hence, the correct order should be:SO₂ > NH₃ > H₂O

 

🔹 Order ii: H₂O > NH₃ > HS⁻ (Dipole moment)
- ✅ This is correct. H₂O has a higher dipole moment (~1.85 D) than NH₃ (~1.47 D), and HS⁻ has the lowest due to its structure and reduced electronegativity difference.

🔹 Order iii: N₂ > O₂ > H₂ (Bond enthalpy)
- ✅ This order is correct. N₂ has the strongest bond (a triple bond), giving it the highest bond enthalpy (~945 kJ/mol), followed by O₂ (~498 kJ/mol) with a double bond, and then H₂ (~436 kJ/mol).

🔹 Order iv: NO⁺ > O₂⁺ (Bond order)
- ✅ This is also correct. According to Molecular Orbital (MO) theory: - Bond order of NO⁺ = 3 - Bond order of O₂⁺ = 2.5 So, NO⁺ has a higher bond order.

Conclusion:
Only statements ii, iii, and iv are correct based on scientific reasoning. 

Final Answer: Option (3): ii, iii, iv only