Which allotropic form of sulphur is thermodynamically stable at room temperature ?

Answer

To determine which allotropic form of sulfur is thermodynamically stable at room temperature, we can follow these steps:

### Step 1: Identify the Allotropic Forms of Sulfur
Sulfur exists in several allotropic forms, including:
- Rhombic sulfur (orthorhombic)
- Monoclinic sulfur
- Alpha sulfur
- Beta sulfur

### Step 2: Determine Stability at Room Temperature
Among these forms, rhombic sulfur is known to be the most stable at room temperature. This stability is due to its lower energy state compared to the other allotropes.

### Step 3: Characteristics of Rhombic Sulfur
- **Color**: Bright yellow
- **Molecular Structure**: It exists as S8 molecules, which have a crown or puckered ring structure. In this structure, each sulfur atom is bonded to two other sulfur atoms, with two lone pairs remaining on each atom.
- **Solubility**: Rhombic sulfur is insoluble in water but can dissolve in organic solvents like benzene, alcohol, ether, and carbon disulfide.
- **Conductivity**: It has low thermal and electrical conductivity.

### Step 4: Conclusion
Thus, the allotropic form of sulfur that is thermodynamically stable at room temperature is rhombic sulfur.

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