Tag: man made materials

Questions Related to man made materials

When plastics are burnt toxic substances are released into air causing ___________ pollution.

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  1. water

  2. air

  3. soil

  4. None of these

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Correct Option: B
Explanation:

When plastics are burnt toxic substances are released into $air$ causing air pollution. The sentence is self-explanatory.

We come to a conclusion, that plastics are bad conductors of electricity from the following.

chemistry man made materials environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

  1. Refrigerators and freezers have a plastic foam core

  2. Electrical wires have a plastic covering

  3. Cooking pans have plastic handles

  4. We use to prepare parachutes

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Correct Option: A,B,C
Explanation:

Most of the commonly used household electronics like freezers, washing machine, etc are made of plastic since it is the bad conductor of electricity.

Which of the following is/are reasons of using plastics?
1.They are transparent.
2. They are cheap.
3. They can be moulded into diffrent shapes.

chemistry man made materials environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

  1. (1) only

  2. (2) only

  3. (1) and (3) only

  4. (2) and (3) only

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Correct Option: D
Explanation:
All three are correct. But the reason for their vast use is the less expenditure and re-usability. 
With the increased knowledge of plastics and the improved capabilities of machining equipment, the industry is now capable of producing plastic components to the same exacting standards as metallic components.
Plastics are cheaper than metals.  They are transparent and elastic material that could be molded when heated. Plastics are easy to reuse as they can be molded into different shapes can be designed for resist impact and dents, making it durable, strong, and stable.


Fibre obtained by chemical treatment of wood pulp is called:

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  1. natural Silk

  2. rayon

  3. nylon

  4. polyster

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Correct Option: B
Explanation:
Natural Silk: The protein fibre of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons.
Rayon: Rayon is a manufactured regenerated cellulose fibre. It is made from purified cellulose, primarily from wood pulp, which is chemically converted into a soluble compound.
Nylon: Nylon is a strong, light synthetic fibre. Nylon thread is made from the polymerization of an amine and an acid chloride. 
Polyester: Polyester is a synthetic polymer made of purified terephthalic acid or its dimethyl ester dimethyl terephthalate and mono ethylene glycol. 

Hence, the correct option is $B$

Which is NOT the general characteristics of plastics?

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  1. Good electrical insulators

  2. Acceptable acoustic insulation

  3. Resistant to corrosion and many chemical factors

  4. Have a high production cost

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Correct Option: D
Explanation:
The properties and characteristics of most plastics (though not always fulfilled in certain special plastics) are these:
Easy to work and shape,
Have a low production cost,
Possess low density,
Tend to be waterproof,
Good electrical insulators,
Acceptable acoustic insulation,
Good thermal insulation, but most can not withstand very high temperatures,
Resistant to corrosion and many chemical factors;

The IUPAC name for Teflon is:

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  1. polytrifluoroethane

  2. polytetrafluoroethane

  3. polytrifluoroethylene

  4. polytetrafluoroethylene

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Correct Option: D
Explanation:
The IUPAC name of Teflon is Polytetrafluoroethylene (PTFE) which is a synthetic fluoropolymer of tetrafluoroethylene.  $ (C _2F _4) _n$. 

Teflon constitutes:

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  1. carbon,flourine & hydrogen

  2. carbon,chlorine & hydrogen

  3. carbon & flourine

  4. carbon & chlorine

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Correct Option: C
Explanation:
Teflon is the brand name of Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene. The constituents of tetrafluoroethylene are carbon and fluorine formula is $ (C _2F _4) _n$. 

Which of the following is thermosetting polymer?

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  1. Nylon

  2. Sealing wax

  3. Polysiloxanes

  4. Both B and C

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Correct Option: C
Explanation:

Thermosetting polymers: These polymers are cross linked or heavily branched molecules, which on heating undergo extensive cross linking in moulds and again become infusible. These cannot be reused. Some common examples are polysiloxanes, bakelite, urea- formaldehyde resins, etc.

Three-dimensional molecules with cross-links are formed in the case of a:

chemistry man made materials environmental impact: plastics plastic plastic plastic waste garbage in, garbage out

  1. thermosetting plastic

  2. thermoplastic

  3. both (a) and (b)

  4. none of the above

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Correct Option: A
Explanation:

Thermosetting plastic consists of chain of the  molecules which are cross-linked, with each other when heated. When thermosetting plastics cross-link, the molecules create a permanant, network  which is a $3-D$ structure and can be considered one giant molecule. Once cured, thermosetting plastic cn not be remelted, in the same way that cured concrete cannot be reset. 

Garden chairs made of plastic strips and plastic articles get faded, worn out and cracked in sunlight, mainly because of:

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  1. Low melting point of plastic

  2. Ultraviolet rays

  3. Heat

  4. The red colour

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Correct Option: B
Explanation:

Garden chairs made of plastic strips and plastic articles get faded, worn out and cracked in sunlight, mainly because of UV rays. All types of UV can cause a photochemical effect within the polymer which can lead to degradation of some sort to the materials. Absorbed UV energy can exits the photon in a plastic, exciting the photons can create free radicals. Those free radicals can cause breaks in the polymer bonds.