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NEET Chemistry Solved Question Paper 2013

Multiple Choice Questions

51.

Which of the following aldoses gives an optically active compound upon reaction with warm dilute nitric acid ?

Only compound (c) will give an optically active compound upon reaction with warm dilute HNO₃ , while other will give meso diacids.

52.

During dehydration of alcohols to alkenes by heating with conc. H₂SO₄, the initial step is :

formation of an este
protonation of alcohol molecule
formation of carbocation
elimination of water

protonation of alcohol molecule

The initial step during dehydration of alcohols is protonation of the alcohol molecule.

53.

CH₃CHO $\overset{Oxidation}{\to}$ (A0 $\overset{{PCl}_{5}}{\to}$ (B) $\overset{{CH}_{3} COONa}{\to}$ (c) .Compond (C) is :

(CH₃CO)₂O
CH₃COCH₃
CH₃COOCH₃
CH₃COOC₂H₅

(CH₃CO)₂O

CH₃CHO $\overset{Oxidation}{\to}$ CH₃COOH $\overset{{PCl}_{5}}{\to}$ CH₃COCl $\overset{{CH}_{3} COONa}{\to}$ (CH₃CO)₂O

54.

Phenol , when it first react with cone. sulphuric acid and then with cone. nitric acid gives :

nitrobenzene
2 , 4 , 6 - trinitrobenzene
o - nitrophenol
p - nitrophenol

o - nitrophenol

-SO₃H groups are knocked out on boiling with H₂O.

55.

By adding sodium dodecyl sulphate, during the electrophoresis of proteins, it is possible to :

determine a protein's isoelectric point
determine an enzyme's specific activity
determine the amino acid composition of the protein
presence a proteins native structure and biological activity

presence a proteins native structure and biological activity

Adding sodium dodecyl sulphate during electrophoresis of amino acids preserve the proteins native structure and biological activity .

56.

In the $α$ -helix , the hydrogen bonds

are roughly parallel to the axis of the helix
are roughly perpendicular to the axis of the helix
occur mainly between electronegative atoms of the R groups
occur only between some of the amino acids of the helix

are roughly parallel to the axis of the helix

In a-helix structure, H-bonds are parallel to the axis of helix

57.

The strongest acid among the following compound is :

HCOOH
CH₃CH₂CH(Cl)COOH
ClCH₂CH₂CH₂COOH
CH₃COOH

CH₃CH₂CH(Cl)COOH

CH₃CH₂CH(Cl)COOH is the strongest acid due to the presence of strong electron withdrawing group Cl at a carbon atom.

58.
Which ofthe following is true regarding teflon ?

It is a linear, unbranched polymer of tetrafluoro ethylene

It has very high thermal stability

Polymer molecules are associated by strong dipole-dipole attraction

All of the above

All of the above

Due to symmetry of F₂C = CF₂ and strength of C-F bond , branching does not take place and a linear chain teflon is always formed. High bond energy of C-F bond gives high thermal stability to polymer . Large electronegativity difference of 'C' and F makes C-F bond highly polar.