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(A) In natural rubber, the polyisoprene ...

(A) In natural rubber, the polyisoprene chains exist as coiled structure.
(R) In polyisoprene Cis-configured chains are held together by weak Vander waals interactions.

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

(A) : Natural rubber is polyisoprene. (R): Natural rubber gives 2-methyl 1, 3 butadiene when it is heated to high temperature in the absence of air.

(A) : Natural rubber is elastic and non-cryslalline. (R) : Weak vander Waal's forces are present.

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

Regarding secondary structure of a protein, correct statement(s) is/are (A) peptide bonds possess regional planarity (B) C = O and -NH- of different peptide chains are held by Van der Waal attarctions (C ) closely packed arrangement so as to minimise repulsion between ''R'' groups.

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 ?

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) .

AAKASH SERIES-POLYMERS-OBJECTIVE EXERCISE - 4
  1. (A) Melamine is a thermosetting polymer (R) Melamine is a condensati...

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  2. (A) Melamine polymers are used to prepare unbreakable crockery items. ...

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  3. (A) Vulcanised Rubber suits industry than natural Rubber. (R) Elasti...

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  4. (A) Rubber latex is colloidal dispersion in water with negatively char...

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  5. (A) Ebonite contain a high percentage of sulphur. (R) Ebonite is a h...

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  6. (A) The process of vulcanization can be accelerated by Zno or zinc ace...

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  7. (A) Position of double bond in poly isoprene can be detected by ozonol...

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  8. (A) Neoprene is a synthetic Rubber. (R) Neoprene is obtained from ch...

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  9. (A) The P.D.I of synthetic polymer is greater than one. (R) Syntheti...

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  10. (A) P.H.B.V is used in spaciality packing. (R) P.H.B.V is a Biodegra...

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  11. (A) Biodegradable polymers are ecofriendly. (R) Biodegradable polyme...

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  12. (A) Poly glycolic acid is used as post operative sutures. (R) Poly g...

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  13. (A) Poly vinyl pyrrolidone is an addition homo polymer. (R) Poly vin...

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  14. (A) In the preparation of plexi glass acetone is used. (R) Poly meth...

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  15. (A) Buna-N is also known as G.R.A. (R) Buna-N is a synthetic Rubber.

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  16. (A) The inter molecular forces in thermosetting polymer is strongest a...

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  17. (A) Dextron is a non biodegradable polymer. (R) Dextron is used in s...

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  18. (A) In natural rubber, the polyisoprene chains exist as coiled structu...

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  19. (A) Bakelite is a thermosetting polymer. (R) Bakelite is a cross-lin...

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  20. (A) Chloroprene is a synthetic rubber. (R) Synthetic rubbers may be ...

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