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(A) Vulcanised rubber is stiff and has l...

(A) Vulcanised rubber is stiff and has little tendency to absorb water.
(R) Vulcanisation introduces sulphur bridges between polymer chains.

A

Both (A) and (R) are true and (R) is the correct explanation of (A)

B

Both (A) and (R) are true and (R) is not the correct explanation of (A)

C

(A) is true but (R) is false

D

Both (A) and (R) are false

Text Solution

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The correct Answer is:
A
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(A) Vulcanised Rubber suits industry than natural Rubber. (R) Elastic properties of Rubber can be reduced due to vulcanization.

(A) : The vulcanised rubber has greater elasticity and tensile strength than crude rubber (R) : Sulphur cross-links are developed

(A) Natural rubber is an elastomer. (R) The intermolecular forces of attraction between the polymer chains are weak van der Waals forces.

(A) The process of vulcanization can be accelerated by Zno or zinc acetate. (R) Vulcanised Rubber is used in tyre industry.

(A) : Natural rubber is an addition polymer. (R) : Natural rubber has cir structure

alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) In alanine, carboxyl group ionises at pK_(a1)=2.34 and ammonium ion at pK_(a2)=9.69 . The isoelectric point of the amino acid is at p^(H) .

alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) N - terminus of the peptide structure is on the

alpha - amino acids are high melting crystalline solids because of the zwitterion structure. They are moderately soluble in water. In acidic medium, alpha - amino acids exist as cations (I) and thus migrate towards cathode under the influence of an electric field. On the other hand, in alkaline medium, alpha - amino acids exist as anions (III) and thus migrate towards anode under the influence of an electric field. However, at some intermediate value of p^(H) , the concentration of the cationic form (I) and anionic form (III) will become equal and consequently the alpha - amino acid will exist primarily as the neutral dipolar ion (II). At this p^(H) , there would be no net migration of the amino acid in an electric field. This p^(H) at which there is no net migration of the amino acid under the influence of an applied electric field is called isoelectric point (pI). Each amino acid has a characteristic isoelectric point. The pH of an amino acid that does not have an ionisable side chain such as alanine isd average of pK_(a) values of the carboxyl group and the protonated amino group. H_(3)overset(+)(N)-overset("R")overset("|")("C")H-COOH overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr H_(3)overset(+)(N)-underset("Zwitterion (II)")(overset("R")overset("|")("C")H)-COO^(-)overset(" "OH^(-)" ")underset(" "H^(+)" ")hArr underset((III))(overset(+)(N)-overset("R")overset("|")("C")H)-COO^(-) Further, the alpha - carbon of all the amino acids (except glycine) is chiral (asymmetric) and hence amino acids can exist in teo stereoisomeric forms i.e., D and L. However, all the nautrally occurring amino acids belong to the L - series. underset("L(-)Glyceraldehyde")(HO-overset("CHO ")overset("| ")underset(" "CH_(2)OH)underset("| ")("C ")-H)" " underset("L-Amino acid")(H_(2)N-overset("COOH")overset("| ")underset("R ")underset("| ")("C ")-H) Which of structural formula of lysine (NH_(2)-overset("COOH")overset("| ")("C ")H-CH_(2)-CH_(2)-CH_(2)-CH_(2)NH_(2)) at pH 13 ?

Assertion (A) : Rain water normally has a pH of 5.6. Reason (R) : The presence of H_(2)SO_(4) and HNO_(3) produced from the oxides of sulphur and nitrogen lower the pH of rain

AAKASH SERIES-POLYMERS-OBJECTIVE EXERCISE - 4
  1. (A) Nylon-6 is obtained by polymerization of caprolactam. (R) Nylon-...

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  2. (A) P.V.C is an addition copolymer (R) P.V.C is used to prepare hand...

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  3. (A) Vulcanised rubber is stiff and has little tendency to absorb water...

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  4. (A) Natural rubber is cis polyisoprene. (R) Isoprene is 2-methyl-1,3...

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  5. (A) Thermosetting polymers are cross linked polymers. (R) Thermosett...

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  6. (A) Natural rubber is an elastomer. (R) The intermolecular forces of...

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  7. (A) Bakelite is prepared by copolymerisation of formaldehyde and pheno...

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  8. (A) Cellulose is natural polymer. (R) Cellulose is obtained from pla...

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  9. (A) Cellulose acetate is a semisynthetic polymer. (R) Natural polyme...

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  10. (A) Poly vinyl chloride is a linear polymer. (R) Poly vinyl chloride...

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  11. (A) L.D.P.E is a branched polymer. (R) L.D.P.E is inert tough and fl...

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  12. (A) Bakelite is a cross linked polymer. (R) Bakelite is formed from...

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  13. (A) Benzene does not undergo polymerisation. (R) Benzene loses aroma...

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  14. (A) Ethylene can undergo polymerisation. (R) Ethylene contain a weak...

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  15. (A) P.V.C is a homopolymer. (R) P.V.C is obtained by the polymerizat...

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  16. (A) Nylon 6,6 is a condensation co-polymer. (R) To prepare nylon-6, ...

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  17. (A) Nylon-6 is a condensation polymer. (R)Nylon-6 is obtained from c...

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  18. (A) Buna-N is an elastomer. (R) Buna-N is rubber like solid with ela...

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  19. (A) Nylon-6, 6 is a fibre. (R) Intermolecular attraction in Nylon 6,...

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  20. (A) Poly styrene is a Thermoplastic polymer. (R) Polystyrene softens...

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