Which of the following used for preparation of bullet proof windows and safty (or) crash helments

Options

A. Kevlar
B. Nomex
C. Lexan
D. None

Explanation

To determine which material is used for the preparation of bulletproof windows and safety (or crash) helmets, we will analyze the options provided: Kevlar, Nomex, Lexan, and Nan.

### Step-by-Step Solution:

1. **Identify the Materials**:
- The options provided are:
- **Kevlar**
- **Nomex**
- **Lexan**
- **Nan**

2. **Evaluate Each Option**:
- **Kevlar**: This is a strong synthetic fiber known for its use in bulletproof vests and bicycle tires. However, it is not primarily known for making windows or helmets.
- **Nomex**: This is a flame-resistant material often used in electrical laminates and circuit boards. It is not typically used for bulletproof windows or crash helmets.
- **Lexan**: This is a type of polycarbonate plastic known for its high impact resistance. It is commonly used in applications like bulletproof windows, safety helmets, race car windows, and various other durable products.
- **Nan**: This option does not correspond to a known material used in this context.

3. **Conclusion**:
- Among the options, **Lexan** is the material that is specifically used for making bulletproof windows and safety helmets. Therefore, the correct answer is **Lexan**.

### Final Answer:
The correct option for the preparation of bulletproof windows and safety (or crash) helmets is **Lexan** (Option 3).

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