Chemistry NCERT Exemplar Solutions Class 12th Chapter Fifteen

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Monomers used in addition to polymerization through free radical pathway should be very pure because even the traces of impurities acts like inhibitors. It leads to the formation of polymers with a shorter chain lengths.

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Proteins have some similar structural similarities with synthetic polyamides. Proteins and polyamides both contain amide linkage.

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Urea-formaldehyde resin is used in laminated sheets. The monomer involved in the formation of urea formaldehyde resin is urea and formaldehyde.

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Polymers that possess amide linkage are termed as nylon. Fibers have a strong intermolecular force of attraction like hydrogen bonding. It leads to the close packing of the structure which imparts the crystalline nature.

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Free radicals are generated from benzoyl peroxide. Alkanes, dienes are polymerized in the presence of free radical inhibitors like benzoyl peroxide, acetyl peroxide. For example, benzoyl peroxide inhibitor is used for the polymerization of ethene to polythene. First, phenyl peroxide radicals are formed which are added to the double bond of ethene generating a new and larger free radical.

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Cis-polyisoprene has a coiled structure which consists of various chains held together by weak Van there Waals force of attraction. It can be stretched like a spring and thus, has elastic properties.

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A vulcanisation process is used to improve the physical properties of natural rubber. This process consists of heating a mixture of raw rubber with sulphur and an appropriate additive at a temperature range between 373 K to 415 k. Sulphur forms cross links at the reactive sites of double bonds during vulcanization, stiffening the rubber.

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Melamine formaldehyde polymer is formed by the condensation polymerization of melamine and formaldehyde.  This is resin intermediate.

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Yes, nucleic acids, proteins, and starch can be considered step growth polymers because this type of polymerization involves a condensation reaction between two monomers. Loss of simple molecules such as water, alcohol results in this type of polymerization and it results in the formation of high molecular mass polymers.