Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

51.

The IUPAC name for the formula :

 is :

  • 2-methyl-2-butenoic acid

  • 3-methyl-3-butenoic acid

  • 3-metyl-2-butenoic acid

  • 2-methyl-3-butenoic acid


C.

3-metyl-2-butenoic acid

IUPAC name is 3-methyl-2-butenoic acid .


52.

CH3COOC2H5 with excess of C2H5MgBr and hydrolysis gives :

  • C2H5-C(CH3)=O

  • (C2H5)2-C(CH3)-OH

  • (CH3)2-C=O

  • (CH3)2-C(C2H5)-OH


B.

(C2H5)2-C(CH3)-OH

When esters react with excess of Grignard reagent , 3° alcohol is formed .


53.

Cannizaro's reaction is exhibited by :

  • HCHO

  • CH3CHO

  • CH3CH2CHO

  • CH3CH2CH2CHO


A.

HCHO

Aldehydes which do not contain any α-hydrogen atom shows Cannizaro's reaction , eg , HCHO , C6H5CHO etc


54.

Natural rubber is a polymer of :

  • cis-isoprene

  • trans-isoprene

  • co-cis and trans isoprene

  • None of the above


A.

cis-isoprene

Natural rubber is a polymer of cis-isoprene .


55.

Chloroform , on exposing to air and sunlight produce :

  • chloropicrin

  • phosgene

  • carbon tetrachloride

  • benzene


B.

phosgene

Chlorofonn is oxidised to poisonous phosgene in the presence of air as :

CHCl312O2  COCl2phosgene + HCl

Therefore , chloroform is stored in dark coloured bottles to protect it from light .


56.

Which of the following can exhibit keto-enol tautomerism ?

  • H-CO||-H

  • (CH3)3C-CO||-H

  • CH3-CO||-H

  • CCl3-CO||-H


C.

CH3-CO||-H

Tautomerism is a special kind of functional isomerism in which the isomers exist in dynamic equilibrium with each other .It arises due to migration of hydrogen atom from one polyvalent atom to the other within the same molecule .The isomers thus obtained are called tautomers .

Thus , HCHO , CCl3CHO and (CH3)3CCHO do not show tautomerism due to the absence of α hydrogen atom w.r.t carbonyl (2(-)C=O) group while CH3CHO shows tautomerism as 


57.

The increasing order of acidity is :

  • CHCl2COOH , CH2ClCOOH , CH3COOH

  • CH3COOH , CHCl2COOH , CH2ClCOOH

  • CH2BrCOOH , CH2ClCOOH , CH3COOH

  • CH2BrCOOH , CH2ClCOOH , CHCl2COOH


D.

CH2BrCOOH , CH2ClCOOH , CHCl2COOH

The acidity of halogen acids depends upon the number , nature and position of halogen atom .Greater the electron withdrawing influence of halogen atom , stronger will be the acid and atoms acidic strength also increases .Thus , the increasing order of acidity is :

CH2BrCOOH < CH2ClCOOH < CHCl2COCH


58.

Williamson's synthesis is used to prepare :

  • bakelite

  • PVC

  • acetone

  • diethyl ether


D.

diethyl ether

When sodium ethoxide react with ethyl bromide , it gives diethyl ether .

CH3CH2O sodium ethoxide Na + Br CH2CH3ethyl bromide  CH3CH2OCH2CH3

This reaction is known as Williamson's synthesis .


59.

Invert sugar is a mixture of :

  • glucose and fructose

  • glucose and lactose

  • glucose and galactose

  • only glucose


A.

glucose and fructose

C12H22O11sucrose[α]D = + 66.5° + H2HCl C6H12O6D (+) glucose[α] = + 52.5° +  C6H22O6D (-) fructose[α]D = - 92.4°

Sucrose is dextrorotatory and the resulting solution is laevorotatory with specific rotation of -39.9° because fructose has a greater specific rotation .Since , there is a change in sign from dextrorotatory to laevorotatory , the reaction is called inversion reaction and thus , sucrose (obtained from glucose and fructose) is called invert sugar .


60.

Glucose has following functional group :

  • aldehyde

  • aldehyde and alcohol

  • alcohol

  • ketone and alcohol


B.

aldehyde and alcohol

Structure of glucose is as 

CHO-(CHOH)4-CH2OH

Hence , glucose contains both aldehyde and alcohol groups .