Assertion and Reason Questions on Class 12 Chemistry Chapter 15 Polymers

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Assertion and Reason Questions on Class 12 Chemistry Chapter 15 Polymers

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.
(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If the Assertion is incorrect but Reason is correct.

Q.1. Assertion : Olefinic monomers undergo addition polymerisation.
Reason : Polymerisation of vinylchloride is initiated by peroxides/ persulphates.

Answer a

Q.2. Assertion : Teflon has high thermal stability and chemical inertness.
Reason : Teflon is a thermoplastic.

Answer (b) Due to the presence of strong C–F bonds, teflon has high thermal stability and chemical inertness.

Q.3. Assertion : Bakelite is a thermosetting polymer.
Reason : Bakelite can be melted again and again without any change.

Answer (c) Bakelite can be heated only once.

Q.4. Assertion : In vulcanisation of rubber, sulphur cross links are introduced.
Reason : Vulcanisation is a free radical initiated chain reaction.

Answer (b) Vulcanisation is a process of treating natural rubber with sulphur or some compounds of sulphur under heat so as to modify its properties. This cross-linking give mechanical strength to the rubber.

Q.5. Assertion : The time of vulcanisation and temperature is increased by adding accelerators.
Reason : By vulcanising, a material of high tensile strength can be obtained.

Answer (d) The time of vulcanisation is reduced by adding accelerators and activators.

Q.6. Assertion : Most of the Synthetic polymers are not biodegradable.
Reason : Polymerisation process induces toxic character in organic molecules.

Answer (c)

Q.7. Assertion (A) : Low density polythene is used in the insulation of electricity carrying wires.
Reason (R) : Low density polythene is chemically inert and tough.

Answer Answer: (b)

Q.8. Assertion (A) : Zeigler-Natta catalyst is a mixture of triethylaluminium and titanium tetrachloride.
Reason (R) : Zeigler-Natta catalyst is used to make low density polythene.

Answer Answer: (c)

Q.9. Assertion (A) : PTFE has high thermal stability and chemical inertness.
Reason (R) : It is a thermoplastic.

Answer Answer: (b)

Q.10. Assertion (A) : Polyamides are best used as fibres because of high tensile strength.
Reason (R) : Strong intermolecular forces (like hydrogen bonding within polyamides) lead to close packing of chains and increase the crystalline character, hence provide high tensile strength to polymers.

Answer Answer: (a)

Q.11. Assertion (A) : 5% of sulphur is added to natural rubber for manufacturing tyre tubes.
Reason (R) : It acts as a cross linking agent and thus makes the rubber stiffer.

Answer Answer: (a)

Q.12. Assertion (A) : Network polymers are thermosetting.
Reason (R) : Network polymers have high molecular mass.

Answer Answer: (b)

Q.13. Assertion (A) : Ordinary rubber is an elastomer.
Reason (R) : The intermolecular forces of attraction between the polymer chains are weak vander Waals’ forces.

Answer Answer: (a)

Q.14. Assertion (A) : Rayon is a semi synthetic polymer and is taken as a better choice than cotton fabric.
Reason (R) : Mechanical and aesthetic properties of cellulose can be improved by acetylation.

Answer Answer: (b)

Q.15. Assertion (A) : Olefinic monomers undergo addition polymerisation.
Reason (R) : Polymerisation of vinylchloride is initiated by peroxides/persulphates.

Answer Answer: (b)

Q.16. Assertion (A) : Polytetrafluoroethene is used in making non-stick cookwares.
Reason (R) : Fluorine has highest electronegativity.

Answer Answer: (b)

Q.17. Assertion (A) : Phenol-Formaldehyde polymer is a thermosetting polymer.
Reason (R) : It can be melted time and again without any change.

Answer Answer: (c)

Q.18. Assertion (A) : For making rubber synthetically, isoprene molecules are polymerised.
Reason (R) : Neoprene (a polymer of chloroprene) is a synthetic rubber.

Answer Answer: (d)

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