The incorrect statement among the follwing is

Options

A. a. `C_(60)` is an allotropic form of carbon.
B. b. `O_(3)` is an allotropic form of oxygen
C. c. `S_(8)` is only allotropic form of sulphur
D. d. red phosphorus is more stable in air than white phosphorus.

Explanation

To determine the incorrect statement among the options provided, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement A: C60 is an allotropic form of carbon.**
- **Analysis:** Carbon has several allotropes, including diamond, graphite, and C60 (also known as buckminsterfullerene). Therefore, this statement is **true**.

2. **Statement B: O3 is an allotropic form of oxygen.**
- **Analysis:** Oxygen exists primarily in two allotropes: O2 (dioxygen) and O3 (ozone). Hence, this statement is also **true**.

3. **Statement C: Acid is the only allotropic form of sulfur.**
- **Analysis:** This statement is **incorrect** because sulfur has multiple allotropes, including rhombic sulfur (α-sulfur), monoclinic sulfur (β-sulfur), and plastic sulfur. The term "acid" likely refers to "sulfur" in its various allotropes, but it is not the only form. Therefore, this statement is **false**.

4. **Statement D: Red phosphorus is more stable in air than white phosphorus.**
- **Analysis:** White phosphorus is known to be highly reactive and unstable in air, while red phosphorus is more stable. Thus, this statement is **true**.

### Conclusion:
The incorrect statement among the options is **Statement C: Acid is the only allotropic form of sulfur.**

---