Name the lightest solid non-metal having the highest tensile strenght.

Explanation

To solve the question, we need to identify the lightest solid non-metal that has the highest tensile strength. Here’s a step-by-step breakdown:

### Step 1: Understand the Terms
- **Lightest Solid Non-Metal**: We need to identify solid non-metals and determine which one has the lowest atomic mass.
- **Tensile Strength**: This refers to the maximum amount of tensile (stretching) stress that a material can withstand before failure.

### Step 2: Identify Solid Non-Metals
The common solid non-metals include:
- Carbon (C)
- Phosphorus (P)
- Sulfur (S)
- Selenium (Se)
- Boron (B)

### Step 3: Determine the Atomic Mass
Next, we check the atomic masses of these solid non-metals:
- Boron (B): Atomic mass ≈ 10.81 g/mol
- Carbon (C): Atomic mass ≈ 12.01 g/mol
- Phosphorus (P): Atomic mass ≈ 30.97 g/mol
- Sulfur (S): Atomic mass ≈ 32.07 g/mol
- Selenium (Se): Atomic mass ≈ 78.96 g/mol

From this, we see that Boron has the lowest atomic mass among the solid non-metals.

### Step 4: Check Tensile Strength
Now, we need to confirm which of these solid non-metals has the highest tensile strength.
- Boron is known for its high tensile strength, especially in its crystalline form.

### Conclusion
Based on the analysis, the lightest solid non-metal with the highest tensile strength is **Boron (B)**.

### Final Answer:
**Boron (B)**

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