Question 1:
Why Is Tar Used in Making the Roads?
Tar which is made using crude oil, is used for making roads due to the following reasons:
Answer:
- Vehicles do not skid on the tar-coated surface.
- It does not get washed away by rainwater.
- Snow quickly melts on the tar-covered surface.
Question 2:
Electric Wires Are Made Up of Metals and Are Covered by Plastic. Why?
Answer:
- Electric wires are made of metals as they are good conductors of electricity.
- The plastic coating on the surface of electric wires acts as an insulator. It is done to avoid electric shocks if someone accidentally contacts the electrical wire.
Question 3:
Why Are Safety Helmets Made Using Certain Forms of Plastics?
Answer:
Certain types of plastic are used to make helmets due to the following reasons:
- Plastic is cheap, and light weighed.
- It can be moulded easily.
- It does not break easily. The thermosetting plastics do not get affected even with normal heat or fire. They require very intense heat to be melted.