Test: Synthetic Fibres & Plastics- 3 - Class 7 MCQ

Synthetic fibres do not absorb moisture and polyester is not derived from cellulose, it is a synthetic fibre.

Higher the water absorption capacity, more will be the final weight. Thus, the correct order of their final weights will be, Wool > Cotton > Silk > Nylon.

Clothes made up of synthetic fibres do not absorb water and do not allow the air to pass through. In hot and humid weather, these clothes stick to the body and make us feel uncomfortable.

The correct option is C.
Polyethylene is the thermoplastic that can be rolled into sheets.
Polyvinyl chloride (PVC) is one type of thermoplastic polymer that is currently construction-related to simple electric wire insulation and coatings.
 Bakelite is a kind of thermosetting plastic which is a bad conductor of heat and electricity. Because of this property it is used for making electric plugs, switches, plug boards, etc.

(i) All plastics do not have the same arrangement of monomer units.
True. Plastics are polymers, and they can have different arrangements of monomer units (e.g., linear, branched, or cross-linked).

(ii) Melamine resists fire and can tolerate heat better than other plastics.
True. Melamine is known for its fire-resistant properties and can withstand higher temperatures compared to many other plastics.

(iii) Plastics with cross-linked monomers are also known.
True. Cross-linked plastics, also known as thermosetting plastics, have a network of bonds that make them more rigid and heat-resistant.

(iv) Plastics have limited applications.
False. Plastics have a wide range of applications in various industries, including packaging, construction, electronics, automotive, and many more.

Therefore, the true statements are:

(i), (ii), and (iii).

The correct option is Option B.

The types that resemble silk are often called artificial silk. It is obtained by chemical treatment of wood pulp of cotton. The fibre is used to make textiles for clothing and other purposes. Rayon production involves solubilizing cellulose.

Spandex, Lycra or elastane is a synthetic fiber known for its exceptional elasticity. It is a polyether-polyurea copolymer that was invented in 1958 by chemist Joseph Shivers at DuPont's Benger Laboratory in Waynesboro, Virginia.

Acrylic fiber is a synthetic fiber that closely resembles wool in its character. Acrylic fiber is a synthetic fiber that closely resembles wool in its character. It can be used 100% alone, or in blends with other natural and synthetic fibers.

Nylon, the first synthetic fiber in the "fully synthetic" sense of that term, was developed by Wallace Carothers, an American researcher at the chemical firm DuPont in the 1930s. It soon made its debut in the United States as a replacement for silk, just in time for the introduction of rationing during World War II.

Polyester is a water-resistant synthetic fibre which makes it ideal for making garments and jackets that are to be used in wet or damp environment.

The correct option is B.
The permanent press or perma press setting is basically for polyester fabrics. ... The warm air dries the garments, but the cool air "sets" the garment, so it resists wrinkles.
The modern non-stick pans were made using a coating of Teflon (polytetrafluoroethylene or PTFE). PTFE was invented serendipitously by Roy Plunkett in 1938, while working for a joint venture of the DuPont company.
Rayon is made from cellulose obtained from wood pulp–usually from pine, spruce, or hemlock trees—and cotton linters, which are residue fibres clinging to cotton seed after the ginning process. 
Nylon has since become a popular choice, as it has excellent wind resistance, good elasticity, mildew resistance, and is comparatively cheaper. ... Nylon fabric for parachutes is woven in a specialized manner with extra thick threads to create a pattern of small squares – this is known as ripstop nylon.
 

Correct Answer :- b

Explanation:- Conduction of heat and electricity requires free electrons. Plastics, whose molecules are made from long combinations of carbon and hydrogen atoms, have few or no free electrons.

 

Ropes made by nylon are used in cranes and elevators.

The most common type of chemical reaction used to make polyester takes place at high temperatures in a vacuum. A petroleum by-product, alcohol, and carboxyl acid are mixed to form a compound known as monomer or “ester.” This reaction is known as polymerization.
Polyester is a synthetic petroleum-based fibre, and is therefore a non-renewable carbon-intensive resource. Nearly 70 million barrels of oil are used each year to make polyester around the world, which is now the most commonly used fiber in making clothes.
 

Plastics are inflammable i.e., they burn easily.

The monomer units of plastics differ in the arrangement, wherein certain cases, they are linear and sometimes cross-linked.

Solution : 

The correct option is Option B.

Fibres are materials which are usually thin and have thread-like structure. They are generally classified as Natural and Synthetic, on the basis of their origin. Natural fibres may be plant fibres like cotton or animal fibres like silk.

As a fiber, jute is biodegradable (it degrades biologically in 1 to 2 years) and compostable.
Coir fiber is the natural fiber extracted from the husk of the coconut. The coir fiber is the thickest and most resistant of all commercial natural fibers.
Acrylic is not easily recycled nor is it readily biodegradable.
Hence the correct answer is (c) as they possess incorrect information.

B is the correct option.
The fibres which are obtained from natural sources like plants(Q) and animals(P) are called natural fibres. Natural fibres are a collection of tiny threads obtained from plants and animals. For Ex: cotton, wool ,Silk ,flax, jute. Flax and jute are the natural fibres obtained from plants
There are two main types of plastics and these are named Thermoplastics(S) and Thermosetting(R) Plastics. Thermoplastics are made up of lines of molecules with few cross linkages. This allows them to soften when heated and to be bent into a variety of shapes and forms. They become stiff and solid again when cold.

Group I: Jute is a natural fibre while others are synthetic. Group II: Melamine is a thermosetting polymer while others are thermoplastics. Group III: Acrylic is not a blended fibre.

Plastics are generally made from petroleum.
Plastics are synthetic materials that are derived from petrochemicals, which are obtained from petroleum or crude oil. Here is a detailed explanation of how plastics are made from petroleum:
1. Petrochemical extraction:
Petroleum, a fossil fuel, is extracted from the earth through drilling and refining processes. It is a complex mixture of hydrocarbons.
2. Cracking:
To obtain the necessary building blocks for plastics, the hydrocarbons in petroleum undergo a process called cracking. This breaks down larger hydrocarbon molecules into smaller ones.
3. Polymerization:
The smaller hydrocarbon molecules, such as ethylene or propylene, are then used as monomers in a polymerization reaction. Polymerization is the process of chemically bonding these monomers together to form long chains called polymers.
4. Plastic production:
The polymers obtained from polymerization are further processed to produce various types of plastics. This involves adding additives, fillers, and other chemicals to achieve desired properties, such as flexibility, durability, and color.
5. Shaping and molding:
The plastic material is then shaped or molded into different forms using processes like injection molding, blow molding, or extrusion. This allows for the production of a wide range of plastic products, from bottles and containers to automotive parts and electronics.
6. Recycling:
While plastics are durable and versatile, they can also contribute to environmental pollution if not properly managed. Recycling is an important step in reducing plastic waste and promoting a circular economy. It involves collecting used plastics, processing them, and using them as raw materials for the production of new plastic products.
In conclusion, plastics are primarily made from petroleum, which is extracted from the earth and processed into polymers through cracking and polymerization. The resulting plastic materials are then shaped and molded into various products. However, it is essential to promote sustainable practices like recycling to minimize the environmental impact of plastics.

Cellulose and Synthetic Fibre
Cellulose:
- Cellulose is a naturally occurring fibre.
- It is found in the walls of plants.
- The walls of plants are made of cellulose.
Synthetic Fibre:
- Synthetic fibre is made from cellulose.
- It is used to make a synthetic fibre that resembles the most expensive natural fibre in appearance.
- This synthetic fibre is also known as "b".
Identification of the Correct Option:
- Looking at the given options, option B is the correct answer.
- Option B shows an image of a synthetic fibre that resembles natural fibre in appearance, which is made from cellulose.
Explanation:
- Cellulose is a naturally occurring fibre found in plants.
- The walls of plants are made of cellulose.
- Cellulose can be used to make synthetic fibres.
- Synthetic fibres made from cellulose resemble the most expensive natural fibres in appearance.
- Option B shows an image of a synthetic fibre that fits this description, hence it is the correct answer.

The correct answer is D as plastic is non biodegradable , and PET  is used for making bottles and rayoon is mixed with wool.

Nylon after flame burn slowly and melt. They are self-extinguishing but drip dangerously. Their odor is like celery and they leave no ash but the fume is very hazardous with the smell of burning hair.
Wool burns slowly and shrinks or curls away from the flame. Will not stay lit after flame is removed. Very little smoke is produced but it smells like burnt hair (wool) or feathers (silk).
 Rayon is a natural fiber made of cellulose, it will burn fast and single quickly with the smell of burning hair.