Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Both rhombic and monoclinic sulphur exist as S$_8$ while oxygen exists as O$_2$.
{Reason (R): Oxygen forms $p\pi$-$p\pi$ multiple bonds with itself and other elements having small size and high electronegativity like C, N, which is not possible for sulphur.
In the light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A).
• C. (A) is correct but (R) is not correct.
• D. (A) is not correct but (R) is correct.

Answer 1

The Correct Option is C

The given question revolves around understanding the existence of different forms of sulfur and oxygen, and the nature of bonding in these elements. Let's analyze the Assertion (A) and Reason (R) provided:

1. Assertion (A): Both rhombic and monoclinic sulfur exist as S₈ while oxygen exists as O₂.
   • Sulfur can form long chains and rings due to its ability to form single bonds with itself. The most common and stable allotrope of sulfur is the S₈ ring, which is true for both rhombic and monoclinic forms of sulfur.
   • Oxygen, on the other hand, typically forms a double bond with itself, resulting in the diatomic O₂ molecule.
   • Thus, Assertion (A) is correct.
2. Reason (R): Oxygen forms $p\pi$-$p\pi$ multiple bonds with itself and other elements having small size and high electronegativity like C, N, which is not possible for sulfur.
   • Oxygen's ability to form strong $p\pi$-$p\pi$ bonds is due to its small size and high electronegativity, allowing for efficient side-to-side overlap of p orbitals, which is not possible for sulfur due to its larger size and lower electronegativity.
   • While the reasoning regarding oxygen's bonding is correct, it does not directly explain why sulfur exists as S₈. The ability of sulfur to form S₈ rings is more a factor of its valence electron configuration allowing for single bonds rather than an inability to form $p\pi$-$p\pi$ bonds.
   • Thus, Reason (R) is not the correct explanation of why sulfur exists as S₈.
3. Conclusion: Given that Assertion (A) is correct but Reason (R) is not the correct explanation, the most appropriate answer is:

(A) is correct but (R) is not correct.

Answer 2

• Assertion (A) is correct because sulphur exists as \( S_8 \) due to its ability to form crown-shaped structures. Oxygen exists as \( O_2 \) due to its smaller size and ability to form \( p\pi \)-\( p\pi \) bonds.
• Reason (R) is incorrect because sulphur’s inability to form \( p\pi \)-\( p\pi \) bonds is due to its larger size, which prevents effective overlap of orbitals.
• Thus, (A) is correct, but (R) is not the correct reason for (A).