Tag: chemistry

Questions Related to chemistry

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 $D$