Answer:

Bullet-proof materials are designed to protect the wearer from the impact of projectiles, such as bullets or shrapnel. They are commonly used in military and law enforcement applications, as well as in certain industries where workers are at risk of exposure to high-velocity projectiles.

Among the polymers listed, polyethylene (option C) is the polymer that is commonly used for making bullet-proof materials.

Polyethylene:
Polyethylene is a lightweight and flexible polymer that has excellent impact resistance and strength. It is widely used in various applications due to its favorable properties, including its low cost, high chemical resistance, and good electrical insulation properties.

Why is polyethylene used for making bullet-proof material?
Polyethylene is used for making bullet-proof material because of its unique combination of properties that make it suitable for this purpose:

1. High tensile strength: Polyethylene has a high tensile strength, which means it can withstand and distribute the force of an impact. This property is crucial for stopping and slowing down projectiles.

2. Energy absorption: Polyethylene has excellent energy absorption properties, which allow it to dissipate the energy of a projectile by deforming and stretching, rather than breaking or shattering. This helps to reduce the impact force on the wearer.

3. Lightweight: Polyethylene is a lightweight material, which is important for applications where mobility and flexibility are required. Bullet-proof vests made from polyethylene are lighter and more comfortable to wear than those made from other materials.

4. Resistance to chemicals and UV radiation: Polyethylene is highly resistant to chemicals and UV radiation, which ensures the longevity and durability of bullet-proof materials made from this polymer.

5. Cost-effective: Polyethylene is relatively inexpensive compared to other materials used for bullet-proof applications, making it a cost-effective choice for manufacturers.

Overall, the combination of high strength, energy absorption, lightweight, and cost-effectiveness makes polyethylene an ideal polymer for making bullet-proof materials.