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311.

The reagent used to distinguish between acetaldehyde and benzaldehyde is

  • Tollen's reagent

  • Fehling's solution

  • 2-4-dinitrophenyl hydrazine

  • semicarbazide


B.

Fehling's solution

(i) Reaction with 2,4-dinitrophenylhydrazine ( Brady's reagent).Acetaldehyde and benzaldehyde react wth 2,4-dintrophenylhydrazine (DNP) to form yellow, orange or red ppt of 2,4-dinitrophenylhydrazones (DNP derivatives).

                  

(ii) Reaction with semicarbazide. Both acetaldehyde and benzaldehyde react with semicarbazide to form.

                 

(iii) Reduction of tollen's reagent both acetaldehyde and benzaldehyde reduce.Tollen's reagent to metallic silver which deposit on the walls of the test tube as bnght silver mirror.

CH3CHOacetaldehyde + 2[Ag(NH3)2]+tollen's reagents + 3OH-  CH3COO-acetate ion+ 2Agsilver mirror+ 4NH3+ 2H2O

(iv)Reduction of Fehling's solution : Acetaldehyde reduces Fehling solution to a red ppt of cuprous oxide.

CH3CHO acetaldehyde+ 2Cu2++ 5OHFehling's solution-  CH3COO- acetate ion+ Cu2O Cuprous oxide(red)+ H2O

However, benzaldehyde does not reduce Fehling's solution.


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312.

(Reductive)Ozonolysis Y + Z

Y can be obtained by Etard's reaction, Z undergoes disproportionation reaction with concentrated alkali. X could be


313.

Acetophenone cannot be prepared easily starting from

  • C6H5CH(OH)CH3

  • C6H5CH3

  • C6H5C≡CH

  • C6H6


314.

Iodoform reaction is answered by all, except

  • CH3-CH(OH)-CH2-COOH

  • CH3CHO

  • CH3-CH2-OH

  • CH3-CH2-CH2OH


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315.

C6H5COOH (ii)(i)NH3 P NaOBr Q (ii) Heat at 460 K(i)Conc. H2SO4 R

R is

  • o-bromo sulphanilic acid

  • sulphanilamide

  • sulphanilic acid

  • p-bromo sulphanilamide


316.

The distinguishing test between methanoic acid and ethanoic acid is

  • litmus test

  • Tollen's test

  • esterficiation test

  • sodium bicarbonate test


317.

The formation of cyanohydrins from a ketone is an example of

  • nucleophilic substitution

  • nucleophilic addition

  • electrophilic addition

  • electrophilic substitution


318.

In the sequence of following reactions

The starting compound P is

  • o- nitro toluene

  • m-nitro toluene

  • o-bromo toluene

  • p-nitro toluene


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319.

Acetic acid is treated with Ca(OH)2 and the product so obtained is subjected to dry distillation. The final product is

  • propanal

  • propanone

  • ethanal

  • ethanol


320.

An organic compound X is oxidised by using acidified K2Cr2O7 solution. The product obtained reacts with phenyl hydrazine but does not answer silver mirror test. The compound X is,

  • 2-propanol

  • Ethanal

  • Ethanol

  • CH3CH2CH3


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