Question 1

Which synthetic polymer is commonly used for making non-stick coating on cooking utensils?

Accepted Answer

Teflon. Teflon is used for non-stick surfaces because it has very low friction and is resistant to heat. It is chemically known as polytetrafluoroethylene (PTFE). This material is also highly resistant to chemical corrosion.

Question 2

Which type of plastic cannot be remoulded upon heating once it has been set?

Accepted Answer

Thermosetting plastics. Thermosetting plastics undergo a chemical change during molding that creates permanent cross-links between chains. Once they are set into a shape, they remain rigid even when subjected to high heat. Bakelite and melamine are prominent examples of this category.

Question 3

What is the primary raw material used for the commercial production of Rayon?

Accepted Answer

Cellulose. Rayon is produced from natural cellulose found in wood pulp or cotton linters. It is considered a semi-synthetic fiber because it is a regenerated natural material. This fiber is often called 'artificial silk' due to its shiny appearance.

Question 4

Which of the following is the first fully synthetic fiber made by man?

Accepted Answer

Nylon. Nylon was developed in the 1930s without using any natural raw materials like plant fibers. It is synthesized entirely from coal, water, and air. Its high strength and elasticity make it ideal for making parachutes and ropes.

Question 5

Which plastic is widely used for manufacturing electrical switches and handles of pressure cookers?

Accepted Answer

Bakelite. Bakelite is a poor conductor of electricity and heat, making it safe for electrical and kitchen use. It is a thermosetting polymer that does not soften at high temperatures. It was the first plastic made from synthetic components.

Man-Made Materials — Set 1