Free Synthetic Fibres and Plastics 03 Practice Test - 8th Grade
Question 1
The practice of breeding silkworms for the production of raw silk is known as:
SOLUTION
Solution : B
Sericulture, or silk farming, is the cultivation of silkworms to produce silk.
Question 2
Based on their structure, all plastics are linear in nature.
SOLUTION
Solution : B
Based on the connections between their monomer units, plastics are classified as linear and cross-linked plastics.
∙ Linear plastics: the monomer units are connected in linear fashion.
∙ Cross-linked plastics: cross-links exists between two linear or branched chains, forming a three-dimensional network.
This arrangement of monomer units define the properties of polymers. Linear polymers can be bent easily, whereas bending cross-linked polymers is difficult.
Question 3
Which of the following material is a mixture of two fibres?
SOLUTION
Solution : C
Polywool is a blend of polyester and wool. The blend is designed to afford the advantages of both the wool and polyester fibres in one fabric, such as wrinkle resistance, increased absorbancy, increased strength etc.
Question 4
Plastic bags are non-biodegradable.
True
False
SOLUTION
Solution : A
A material which is not easily decomposed by natural processes is termed as non-biodegradable. Plastic is generally considered non-biodegradable as it cannot be degraded by bacteria.
Plastic bags and other plastic items, that we use in our daily lives, end up in landfills and are typically buried. Since they do not degrade, they pose a greater environmental threat than the biodegradable wastes do.
Question 5
Around 10 kg of silkworm cocoons are needed to produce 1 kg of silk.
SOLUTION
Solution : A
Silk is a natural fibre obtained from silkworm, which is an insect. The best-known silk is obtained from the cocoons of the mulberry silkworm. A large quantity, around 10 kg of silkworm cocoons, is required to make just 1 kg of silk.
Question 6
Thermosetting plastics are strong, durable and can be remoulded by heating them.
SOLUTION
Solution : B
Thermosetting plastics are those plastics which once moulded cannot be remoulded by heating. They are strong, durable and resists heat to a large extent. The well known examples are bakelite and melamine.
On the other hand, thermoplastics can be repeatedly moulded if they are heated above a specific temperature. For example, PVC, nylon, etc.
Question 7
Identify the cloth materials that are preferred for sportswear.
SOLUTION
Solution : C and D
A sports garment needs to be light in weight, non-absorbent of sweat, easier and faster to dry, etc. Cotton absorbs moisture but does not dry easily. Clothes made of synthetic fibres like polyesters and nylon do not absorb moisture. Instead they help in quickly transporting the sweat from the skin to the outer surface, from where it dries off easily.
Question 8
Plastics are heavier than metals, so they are used in cars, aircrafts and spacecrafts.
True
False
SOLUTION
Solution : B
- Plastic is very light, strong and durable. In addition to these, it can also be moulded into different shapes and sizes.
- So, it is used for various purposes in industries and for the manufacture of household products.
- Since plastic is cheaper, lighter and chemically unreactive as compared to metals, it is used in cars, aircrafts and spacecrafts.
Question 9
Which of the following fibres is used for making parachutes?
SOLUTION
Solution : C
Nylon threads are strong, elastic and lightweight. A nylon wire is stronger than a steel wire having the same diameter. Hence, it is preferred for making parachutes.
Harness straps, tents, sleeping bags, sails, ropes, fishing poles, etc are also made from nylon fibers because of its strength.
Question 10
Modern non-stick cookware and the flat end of an electric iron has a coating of a polymer. Identify the name of the polymer.
Polyester
Teflon
Rayon
PVC
SOLUTION
Solution : B
A non-stick surface can reduce the ability of other materials to stick on it. These surfaces are coated with a synthetic polymer called teflon. Non-stick cookware and the flat end of an electric iron are coated with teflon.