Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

41.

In the following sequence of reactions,

CH subscript 3 minus Br space rightwards arrow with KCN on top space straight A rightwards arrow with straight H subscript 3 straight O to the power of plus on top straight B space rightwards arrow from ether to LiAlH subscript 4 of space straight C
the end product is (C) is

  • acetone

  • methane

  • acetaldehyde

  • acetaldehyde


D.

acetaldehyde

stack CH subscript 3 Br with methy space bromide below space rightwards arrow from negative KBr to KCN of space stack CH subscript 3 CN space with ethane space nitrile space left parenthesis straight A right parenthesis below rightwards arrow with straight H subscript 3 straight O to the power of plus on top space stack CH subscript 3 COOH with ethanoic space acid space apostrophe straight B apostrophe below
space space space space space space space space space space space space rightwards arrow from ether to LiAlH subscript 4 of space stack CH subscript 3 CH subscript 2 OH with ethanol space apostrophe straight C apostrophe below
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42.

Which one of the following sets of monosaccharides forms sucrose?

  • α-D-galactopyranose and α-D- glucopyranose
  • α-D-glucopyranose and β-D-fructofuranose
  • β-D-glucopyranose and α-D-fructofuranose
  • β-D-glucopyranose and α-D-fructofuranose

B.

α-D-glucopyranose and β-D-fructofuranose

Sucrose is composed of α-D-glucopyranose and β-D-fructofuranose units which are joined by α, β-glycosidic linkage between C-1 of the glucose unit and C-2 of the fructose unit.

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43.

Which of the following statements is false?

  • Artificial silk is derved from cellulose

  • Nylon-66 is an example of elastomer

  • The repeat unit  in natural rubber isoprene

  • The repeat unit  in natural rubber isoprene


B.

Nylon-66 is an example of elastomer

Nylon-66 is a fibre as in it the forces of attraction are H-bonding. All other given statement are true. 

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44.

The correct order of decreasing acid strength of trichloroacetic acid (A), trifluoroacetic acid (B), acetic acid (C) and formic acid (D) is 

  • B > A> D > C

  • B  > D > C > A

  • A> B > C  > D

  • A> B > C  > D


A.

B > A> D > C

If an electron withdrawing group (-I showing group) is present, it makes the removal of proton more easy by stabilising the remaining carboxylate ion and thus, makes the acid more acidic. The order of acidity of given compounds is



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45.

Predict the products in the given reaction,


C.

When benzaldehyde is treated with 50% alkali, it undergoes oxidation to give an acid salt as well as a reduction to give an alcohol. This reaction is called Cannizzaro's reaction.

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46.

In the following reaction,


A.

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47.

CH3CHO and C6H5CH2CHO can be distinguished chemically by

  • Benedict test

  • Iodoform test

  • Tollen's reagent test

  • Tollen's reagent test


B.

Iodoform test

CH3CHO and C6H5CH2CHO both being aliphatic aldehydes react with Tollen's reagent, Fehling solution and Benedict solution. So, these reagents cannot be used to distinguish them. CH3CHOreacts with  NaOH and I2 to give yellow crystals of iodoform while C6H5CH2CHO does not react with it.

CH3CHO +3I2 4 NaOH → CHI3 +HCOONa +3NaI +3H2O

C6H5CH2CHO +I +4NaOH → No reaction

Thus, CH3CHO and C6H5CH2CHO can be distinguished by iodoform test. 

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48.

Acetone is treated with an excess of ethanol in the presence of hydrochloric acid. The product obtained is.


D.

When carbonyl compounds are treated with alcohol, they form hemiacetal (hemiketal and acetal/ketal.)

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49.

Among the following compounds, the one that is most reactive towards electrophilic nitration is

  • Benzoic acid

  • Nitrobenzene

  • toluene

  • toluene


C.

toluene

The presence of electron releasing group like -R, -OH etc., increases the electron density at o/p position and thus, makes the benzene ring more reactive (at(o/p position) towards electrophile. On the other hand, electron withdrawing group like-COOH,-NO2 etc. If present, reduces electron density and thus, reduces the activity benzene nucleus towards electrophile.Thus, the order of the given compounds towards electrophilic nitration is

Thus, toluene is most reactive towards electrophilic nitration.

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50.

Which of the following is not condensation polymer?

  • Melamine

  • Glyptal

  • Dacron

  • Dacron


D.

Dacron

Condensation polymers are obtained by bifunctional molecules (monomers) with the elimination of smaller molecules whereas additional polymers are obtained from multiple bonds containing monomers. Neoprene is a polymer of chloroprene (CH2 =C(Cl)-C=CH2) so it is an addition polymer, not a condensation polymer. 

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