Tag: man made materials

Questions Related to man made materials

Consider the following statements-


I. weakest intermolecular forces are present in elastomers.

II. Fibers possess a crystalline nature.


III. Ionic bonds are present in thermoplastic polymers.

Select the correct option from the following:
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  1. I and II

  2. II and III

  3. I and III

  4. I,II and III

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Correct Option: A
Explanation:
Elastomers are rubber like solid polymers in which polymer chains are hold together by weakest intermolecular forces.
Eg : Natural rubber
Fibers are thread-like polymers & can be woven into fabrics. They possess high tensile strength & are crystalline in nature.
Eg ; Nylon $6,6$.

Hence, the correct option is A.

Thermosetting plastics cannot be softened by heating because:

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  1. they are cross linked polymers with hydrogen bonds b/w each other.

  2. they are linear chains of polymers

  3. they are large cross-linked molecules with strong covalent bonds b/w the atoms along each chains

  4. they are large cross-linked molecules with strong electrovalent bonds between the atom along each chain.

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Correct Option: A
Explanation:

Thermosetting polymers are formed from monomers of viscous state which changes irreversibly on heating into an infusible insoluble polymer. They have high crosslinks due to which they are rigid.

Which of the following properties of plastic make it most convenient to use?

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  1. It is non-reactive

  2. Light, strong and durable

  3. Easily remouldable

  4. All of the above

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Correct Option: D
Explanation:

Plastics are non-reactive at room temperature and others are highly reactive.

Because of lower density than metals, plastic is light, strong and durable so can be molded in different shapes and sizes easily.
So all the options are correct, all are properties of plastic.

Option D is correct answer.

Which one among the following is a thermosetting plastic?

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  1. PVC

  2. PVA

  3. Bakelite

  4. Perspex

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Correct Option: C
Explanation:
Bakelite is another name of phenol formaldehyde which is a thermosetting plastic so bakelite is a thermosetting plastic.

Plastic which has cross-linked (3D) structure and is generally made by the condensation polymerization method is called thermosetting plastic. It can't be reused once it is processed.

Which of the following is not correct regarding terylene ?

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  1. Condensation polymer

  2. Synthetic fibre

  3. Step-growth polymer

  4. Known as dacron

  5. Thermosetting plastic

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Correct Option: E
Explanation:

Terylene is a synthetic polymer formed by the condensation polymerization reaction of terephthalic acid and ethylene glycol with the release of a methanol molecule. 


It forms by a step-growth polymerization mechanism in which a bi-functional or multifunctional monomer react to form the first dimer, then trimer, longer oligomer and eventually long-chain polymers. 

It is also called as Dacron and is a thermoplastic, which can be remelted time and again without producing any change.

Which of the following is NOT true?

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  1. Thermosetting plastic are bad conductors of heat and electricity.

  2. Thermoplastics are good conductor of heat and electricity.

  3. Plastic do not get corroded easily.

  4. Plastic is also a polymer.

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Correct Option: B
Explanation:

Thermoplastic polymer can change their properties when heated and cooled. All plastics are bad conductors of heat and electricity.


Option B is correct.

Which of the following is a property of plastic?

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  1. Flame resistant

  2. Non-corrosive

  3. Mouldable

  4. All of the above

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Correct Option: D
Explanation:

The properties of the plastics are as follow:

  • They can be easily molded.
  • They are non-corrosive.
  • They are flame resistant.
  • They are a bad conductor of electricity.
Thus all the properties that are given in the options are properties of plastic.

Coating of melamine plastic is used as :

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  1. good conductor of heat

  2. strong and durable

  3. fire proofplastic

  4. plastic cook ware

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Correct Option: C

Plastics which when moulded once, cannot be softened by heating are called :

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  1. thermosetting plastics

  2. thermoplastics

  3. thermostat plastics

  4. mould plastics

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Correct Option: A

Which material is used for making:
(i) Saucepan handles
(ii) Electric plugs/switches/plugboards

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  1. Bakelite

  2. PVC

  3. Polythene

  4. Polyester

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Correct Option: A
Explanation:

(i) Saucspan handles are made of bakelite as it is a bad conductor of heat.
(ii) Bakelite is also a bad conductor of electricity so the electric plugs, switches, etc. are made of it.