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Polymers and macromolecules - class-VII

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Synthetic fibres are obtained by :

  1. chemical processing of petrochemicals

  2. chemical processing of natural fibres

  3. manual processing of petrochemicals

  4. Both A and B


Correct Option: A
Explanation:

The compounds that are used to make synthetic fibres come from raw materials such as petroleum-based chemicals or petrochemicals. 


These materials are polymerized into a long, linear chemical that bond two adjacent carbon atoms. 

Differing chemical compounds will be used to produce different types of fibers.

Hence the correct option is A.

Synthetic fibres are better than natural fibres because :

  1. they are man made

  2. they are cheaper

  3. they are eco friendly

  4. their length can be controlled


Correct Option: B
Explanation:

Synthetic fibres are cheaper than natural fibres. The synthetic fibers are cheap because they are built from cheap raw materials and produced very efficiently; for example, nylon and polyester are mostly built from oil by-products and are efficiently produced in huge amounts. 

Explain why synthetic fibers are cheaper than natural fibers?

  1. It is easy to prepare

  2. It is prepared by chemicals which are easily available.

  3. Natural fibers are obtain in less quantity.

  4. All of these


Correct Option: D
Explanation:

Synthetic fibers are prepared by chemicals, this chemicals are available in cheap prize so that synthetic fibers can be produced in large quantity. Natural fibers are obtain from the natural sources which are present in the limited quantity.

Which of the following synthetic fiber is used in aerospace?

  1. Nylon

  2. Aramid

  3. Acrylic

  4. All of above


Correct Option: B
Explanation:

Aramid fibers are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in bicycle tires, and as an asbestos substitute. 

State True or False.
Synthetic fibres do not melt on heating.

  1. True

  2. False


Correct Option: B
Explanation:

Synthetic fibres melts on heating.

What cloth should you wear while cooking in the kitchen?

  1. Rayon

  2. Cotton

  3. Polyester

  4. Polycot


Correct Option: B
Explanation:

Synthetic fibers such as rayon, polyester melt on heating. Therefore it is not safe while cooking. It the clothes catch fire it can be disastrous. Cotton cloth is best and safe to wear in such conditions.

Polycot is a mixture of_____________.

  1. Nylon and Wool

  2. Polyester and Cotton

  3. Nylon and Cotton

  4. Polythene and Cotton


Correct Option: B
Explanation:

Polycot is obtained by mixing polyester and cotton.


Option B is correct.

Why is it not advisable to wear synthetic clothes while bursting fire crackers?

(i) All synthetic fibres are prepared by using raw materials of petroleum origin.
(ii) Synthetic fibres catch fire easily.

(iii) On heating, synthetic fibres melt and stick to the body of the person wearing it.

  1. (i) only

  2. (ii) only

  3. (i) and (iii)

  4. (ii) and (iii)


Correct Option: D
Explanation:

Option (D) is correct as;  Synthetic fibres catch fire easily and on heating synthetic fibres melt and stick to the body of the person wearing it.

Which among the following does not belong to synthetic fibres?

  1. Jute

  2. Nylon

  3. Rayon

  4. Teflon


Correct Option: A
Explanation:

 Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, family Malvaceae. 

Jute is one of the cheapest natural fibers, and is second only to cotton in amount produced and variety of uses. Jute fibres are composed primarily of the plant materials, cellulose (major component of plant fibre) and lignin (major components wood fibre). It is thus a ligno-cellulosic fibre that is partially a textile fibre and partially wood. It falls into the bast fibre category (fibre collected from bast or skin of the plant) along with Kenaf, Industrial Hemp, Flax (Linen), Ramie, etc. 

Others belong to the class of Synthetic polymers as they are produced artificially by chemicals.

_______ are manufactured from a mixture of two or more different type of fibers.

  1. Stalk fibers

  2. Blended fibers

  3. Vinyon

  4. Elastoester


Correct Option: B
Explanation:

Blended fibers are manufactured from a mixture of two or more different type of fibers. Mixing fibers allows manufactures to form new textile yarns with distinct advantages. Each fiber retains its separate set of physical and aesthetic characteristics inherent in its design but the fabric acquires new characteristics depending on the type and percent of fibers used. Blends utilize the advantages of all the fibers to counteract the disadvantages of a single fiber. Synthetic fibers can be blended with natural fibers to create a material that is stronger, but more comfortable.

Synthetic fibers are made by :

  1. condensation

  2. hydrolysis

  3. polymerization

  4. none of above


Correct Option: C
Explanation:

Synthetic fabrics are textiles made from man-made rather than natural fibers. Synthetic (chemically produced) fibres are made by joining monomers into polymers, through a process called polymerization. A synthetic fibre, when magnified, looks like plastic spun together. Polymerization is the formation of macromolecules through repetition of basic units. Initially, the various components are solids and first must be converted to a liquid state to be extruded into fibers. The materials are chemically converted, dissolved, or melted, turning into a thick liquid.

Which of the following is a disadvantage of synthetic fibre?

  1. melt before burning

  2. repel moisture

  3. clothes are garishly lustrous

  4. All of the above


Correct Option: D
Explanation:

Clothes made of pure synthetic fibres are garishly lustrous. Synthetic fibres melt before burning. So clothes made of such fibres stick to the skin when in contact with a flame, causing burns. Therefore, they should not be worn in the kitchen or while setting off fireworks. 

Synthetic fibres are generally hydrophobic, i.e., they repel moisture (e.g., sweat) and do not absorb it. They do not allow enough circulation of air either. So clothes made of synthetic fibres are not comfortable to wear as they do not allow sweat to evaporate easily. 

Cellulose dissolved in a mixture of sodium hydroxide (NaOH) and carbon disulphide produces :

  1. Viscose

  2. Rayon

  3. Polyamide

  4. Polyester


Correct Option: A
Explanation:

Cellulose (say, cotton) is dissolved in a mixture of sodium hydroxide (NaOH) and carbon disulphide ($CS _2$, a solvent). A viscous liquid (i.e., a liquid which cannot flow freely) called viscose is obtained. The viscose is then forced through spinnerets (which have small holes) into an acid bath, and filaments of viscose rayon are obtained.

To which of the following does the $4$R principle apply the most?

  1. Synthetic fibre

  2. Natural fibre

  3. Metals

  4. Plastic


Correct Option: D
Explanation:

Plastic follow all the 4R principles: Reduce, reuse, recycle, restore.

Artificial fibres is the other name given to ____________.

  1. plastic

  2. synthetic fibres

  3. plant fibres

  4. animal fibres


Correct Option: B
Explanation:

Artificial fibres is other name given to synthetic fibres. Examples of synthetic fibres are nylon, PVC, polyester, etc.

The first synthetic thermosetting plastics is :

  1. bakelite

  2. mellamine

  3. nylone

  4. PVC


Correct Option: A
Explanation:

Bakelite is the first synthetic thermosetting plastics.

This is the synthetic fibre :

  1. Wool

  2. Cotton

  3. Acrylic

  4. Polystyrene


Correct Option: C
Explanation:

Acrylic is a man-made fiber it resembles wool and hence it is also known as artificial wool or synthetic wool.  In commercial use acrylic is cheaper than natural wool and can be dyed in various colours.

These are the synthetic materials which we come across in our daily life :

  1. plastic

  2. glass

  3. cement

  4. wool


Correct Option: A,B,C
Explanation:

Synthetic materials in daily life are:

$(a)$ Plastic
$(b)$ Glass
$(c)$ Cement
Wool is a natural material which is obtained from sheep.

Commonly used synthetic fabrics are:

  1. polyester

  2. nylon

  3. rayon

  4. acrylic


Correct Option: A,B,C,D
Explanation:
 Fabric  raw material
 Polyester  ester
 Nylon  carpolactam
 Rayon  wood pulp
 Acrylic  polyacryonitrile

The fabrics that are produced entirely from chemicals are known as synthetic fabrics. Examples of synthetic fabrics are nylon, polyester, rayon, and acrylic

Synthetic fibres are made using __________ as raw materials.

  1. woollen products

  2. polymers

  3. cotton

  4. petrochemicals


Correct Option: D
Explanation:

Synthetic fibres are not obtained from natural resource but it is manufactured in a laboratory using petrochemicals. Synthetic fabrics are textiles made from man-made rather than natural fibres. Examples of synthetic fabrics include polyester, acrylic, nylon, rayon, acetate, spandex, latex, Orlon and kevlar. Synthetic (chemically produced) fabrics are made by joining monomers into polymers, through a process called polymerisation. 


Chemicals used to make synthetic fabric include sodium hydroxide and carbon disulfide, which are derived from coal, oil, or natural gas (petrochemicals). Pressure forces the liquid chemicals through tiny holes called spinnerets. As the liquid comes out of the spinnerets and into the air, it cools and forms tiny threads. Manufacturers add artificial dyes to these threads before weaving them into a fabric.

Hence, the correct option is $D$

__________ is a synthetic fibre used for making artificial woollen clothes. 

  1. Acrylic

  2. Polyester

  3. Fibre

  4. Cotton


Correct Option: A

Which of the following changes came regarding dressing styles after 18th century?

  1. People dressed according to their regional codes

  2. People could use styles and materials that were drawn from other cultures and locations

  3. Dressing was limited by the types of clothes and the cost of material available in their region

  4. Clothing styles were strictly regulated by class, gender or status


Correct Option: B
Explanation:

People could use style's and materials that were drawn from other culture and locations. These are the changes came regarding dressing styles after $18^{th}$ century.

State True or False :


It is risky to wear synthetic clothes while working in the kitchen.

  1. True

  2. False


Correct Option: A
Explanation:

The given statement is true.


It is risky to wear synthetic clothes while working in the kitchen. Synthetic fibre may melt on heating.

Match the column I with column II and mark the appropriate choice.

Column I Column II
(A) Natural polymer (i) Rayon
(B) Addition polymer (ii) Bakelite
(C) Copolymer (iii) Silk
(D) Semi-synthetic polymer (iv) Neoprene
  1. (A) $\rightarrow$ (i), (B) $\rightarrow$ (ii), (C) $\rightarrow$ (iv), (D) $\rightarrow$ (iii)

  2. (A) $\rightarrow$ (iii), (B) $\rightarrow$ (iv), (C) $\rightarrow$ (ii), (D) $\rightarrow$ (i)

  3. (A) $\rightarrow$ (ii), (B) $\rightarrow$ (iii), (C) $\rightarrow$ (i), (D) $\rightarrow$ (iv)

  4. (A) $\rightarrow$ (iv), (B) $\rightarrow$ (i), (C) $\rightarrow$ (iii), (D) $\rightarrow$ (ii)


Correct Option: B
Explanation:
 Natural rubber  (iii)
 Addition polymer  (iv)
 Copolymer  (ii)
 Semi-synthetic polymer  (i)

Natural polymer-These polymers are found in plants and animals. Examples are proteins, cellulose, starch, resins rubber and rayon.

The correct option is [B].

Which of the following is not a natural polymer?

  1. Starch

  2. Nucleic acid

  3. Polystyrene

  4. Protein


Correct Option: C
Explanation:

Polystyrene is made of styrene monomer which is a synthetic polymer. The monomer is a liquid petrochemical.

Polystyrene are used in making CD, jewel cases, expanded polystyrene (EPS) Foam products from Foam cups to Foam coolers, etc.

The naturally occurring polymer among the following is:

  1. Rayon

  2. Nylon - $6$

  3. Decron

  4. Proteins


Correct Option: D
Explanation:

NATURAL  POLYMER  -  The polymers found in nature, i.e., from plants & animals are known as natural polymers.
RAYON - Rayon is classified as semisynthetic polymer, as it is manufactured from naturally occuring polymers. It is purified from cellulose.
NYLON - $6$  -  Nylon - $6$ is a synthetic polymer, obtained by heating caprolactum with water at high temp.
DACRON  -  It is also a synthetic polymer. It is formed by interaction of ethylene glycol & terephthalic acid.
PROTEINS  -  Proteins are large macromolecules, containing one or more chains of amino acids. They are held together by peptide bonds. Amino acids are found in living organisms. Hence, they are natural polymer.

Cellulose is a polymer of:

  1. $\alpha -$ galactose

  2. $\alpha -$ glucose

  3. $\beta -$ galactose

  4. $\beta-$glucose


Correct Option: D
Explanation:

Cellulose is an organic compound consisting of a linear chain of several hundred to over ten thousand $\beta$ (1 $\rightarrow$4) linked $D - glucose$ units.

The S in Buna- S refers to:

  1. sulphur

  2. styrene

  3. sodium

  4. just a trade name


Correct Option: B
Explanation:

The S in Buna- S refers to styrene. Buna stands for butadiene and Na for sodium.
Buna-S refers to styrene Butadiene Rubber (SBR). It is copolymer of buta-1,3-diene and styrene in the ratio of 3:1 in the presence of sodium.

Among the following, a natural polymer is____________.

  1. cellulose

  2. PVC

  3. teflon

  4. polyethylene


Correct Option: A
Explanation:

Among the following, cellulose is a natural polymer. It is a polysaccharide.

The soft silk yarn is as strong as compared to:

  1. Cotton

  2. Jute

  3. Steel

  4. Polyster


Correct Option: C
Explanation:

Silk is an elastic, lustrous protein fiber. The soft silk thread is as strong as a comparable steel thread.

Which of the following is not an example of natural polymer?

  1. Wool

  2. Silk

  3. Leather

  4. Nylon


Correct Option: D
Explanation:

Natural polymers occur in nature and can be extracted. 


Examples of naturally occurring polymers are silk, wool, leather, DNA, cellulose and proteins. 


Synthetic polymers are human-made polymers.

Examples of synthetic polymers include nylon, polyethene, polyester, Teflon, and epoxy. 

Hence, option D is the correct option.

______ and ______ yields wool found in South America.

  1. Goat and Sheep

  2. Angora Goat

  3. Llama and Alpaca

  4. Yak and Sheep


Correct Option: C
Explanation:

Llama and Alpaca species found in South America yield wool.

The acrylic polymer must contain :

  1. acrylonitrile monomer.

  2. sodium thiocyanate.

  3. acrylic acid.

  4. sulphuric acid.


Correct Option: A
Explanation:

Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of approx 100,000, about 1900 monomer units. 


For a fiber to be called acrylic, the polymer must contain at least 85% acrylonitrile monomer. Acrylonitrile is an organic compound that is a colorless volatile liquid.

So, the correct option is $A$

State True or False.


Teflon is natural polymer.

  1. True

  2. False


Correct Option: B
Explanation:

There are two types of polymers: synthetic and natural. 


Synthetic polymers are derived from petroleum oil and made by scientists and engineers. Examples of synthetic polymers include nylon, polyethene, polyester, Teflon, and epoxy. 

Natural polymers occur in nature and can be extracted. They are often water-based. Examples of naturally occurring polymers are silk, natural rubber, wool, DNA, cellulose and proteins.

Hence, it is a false statement.

Which of the following is not a synthetic polymer?

  1. Polyisoprene

  2. Polybutadiene

  3. Polyethylene terephathalate

  4. Polyethylene


Correct Option: A
Explanation:

Polyisoprene is a natural polymer made of isoprene as the monomeric unit.

Acetate rayon is prepared from _____.

  1. Acetic acid

  2. Glycerol

  3. Starch

  4. Cellulose


Correct Option: D
Explanation:

Acetate rayon is a organic polymer formed by acetylation of all remaining -OH's of linear cellulose chain. It is a synthetic filament, yarn, or fabric composed of a derivative of the acetic ester of cellulose.

Which of the following is not a synthetic polymer?

  1. polyvinyl chloride

  2. plastic

  3. polystyrene

  4. polyethylene

  5. cellulose


Correct Option: E
Explanation:

Cellulose is not a synthetic polymer. It is a natural polymer.
It is a polysacchardie having molecular formula $(C _6H _{10}O _5) _n$. It has linear chain of $\beta(1\rightarrow 4)$ linked D-glucose units. There are several hundred to many thousands of such units in a chain.  Cellulose is an important structural component of  in the primary cell wall of green plants, many forms of algae and the oomycetes.

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