Given below are two statements :
Statement-I : `alpha` and `beta` forms of sulphur can change reversibly between themselves with slow heating or slow cooling.
Statement-II : At room temperature the stable crystalline form of sulphur is monoclinic sulphur.
In the light of the above statements, choose the correct answer from the options given below:

Options

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

Answer

To solve the problem, we need to analyze the two statements regarding the allotropes of sulfur, namely alpha (rhombic) sulfur and beta (monoclinic) sulfur.

### Step-by-Step Solution:

1. **Understanding Allotropes of Sulfur**:
- Sulfur has several allotropes, with the most common being alpha (rhombic) sulfur and beta (monoclinic) sulfur.
- Alpha sulfur is stable below 369 K, while beta sulfur is stable above this temperature.

2. **Analyzing Statement I**:
- Statement I claims that alpha and beta forms of sulfur can change reversibly between themselves with slow heating or slow cooling.
- This is true because when alpha sulfur is heated above 369 K, it transforms into beta sulfur, and when beta sulfur is cooled below this temperature, it reverts back to alpha sulfur. Therefore, Statement I is **correct**.

3. **Analyzing Statement II**:
- Statement II states that at room temperature, the stable crystalline form of sulfur is monoclinic sulfur.
- This statement is false because at room temperature, which is approximately 298 K (25°C), alpha (rhombic) sulfur is the stable form. Monoclinic sulfur is stable only at temperatures above 95.6°C (368.8 K). Hence, Statement II is **incorrect**.

4. **Conclusion**:
- Since Statement I is true and Statement II is false, the correct answer is that Statement I is correct and Statement II is incorrect.

### Final Answer:
- The correct option is: **Statement I is true, Statement II is false**.