A form of which of the following non-metal is the hardest substance ?

Options

A. Phosphorus
B. Sulphur
C. Iodine
D. Carbon

Explanation

To solve the question "A form of which of the following non-metal is the hardest substance?" we will follow these steps:

### Step 1: Identify the Non-Metals
First, we need to identify the non-metals from the given options:
- Phosphorus
- Sulfur
- Iodine
- Carbon

### Step 2: Understand the Hardness of Non-Metals
Next, we need to consider the hardness of these non-metals. Non-metals can vary in hardness, and we are looking for the hardest one among the options.

### Step 3: Analyze Each Option
- **Phosphorus**: Generally soft and can be found in different forms (white, red, and black phosphorus), but none are particularly hard.
- **Sulfur**: Also a soft non-metal, typically brittle and not hard.
- **Iodine**: A non-metal that is also soft and can be easily broken.
- **Carbon**: This non-metal has several allotropes, including diamond and graphite. Among these, diamond is known to be the hardest natural material.

### Step 4: Conclusion
Based on the analysis, the hardest substance among the non-metals listed is **carbon**, specifically in its allotrope form as **diamond**.

### Final Answer
The answer to the question is **carbon**.

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