NEETprep Bank NEET Chemistry Alcohols,Phenols and Ethers Questions Solved


Which of the following will not form a yellow precipitate on heating with an alkaline solution of iodine?

(a) CH3CH(OH)CH3                                  (b) CH3CH2CH(OH)CH3

(c) CH3OH                                               (d) CH3CH2OH

(c) An organic compound form yellow precipitate of iodoform with I2 in presence of alkali, if it has

CH3CO- group directly or it             HCH3-C||-            OHhas group.

(a) CH3CH(OH)CH3 + I2 NaOH CH3COCH3 + 2HI + 3NaI  + CH3COONa + 3H2O

     CH3COCH3 + 3I2 + 4NaOH  CHI3 + 3NaI + CH3COONa + 3H2O

                                                 yellow ppt.

(b) CH2-CH2CH(OH)CH3 + I2    + 2HI

It gives iodoform test

(c) CH2OH + I2 HCHO + 2HI

It does not have methyl ketone group, so it does not give yellow ppt with I2 in presence of alkali.

(d) CH3CH2OH + I2  CH3-C||-H            O + 2HI

It gives iodoform test

presence of -COCH3, it gives Haloform reaction.

Difficulty Level:

  • 10%
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  • 62%
  • 15%

n-propyl alcohol and iso-propyl alcohol can be chemically distinguished by which reagent 

(a) PCl5

(b) reduction

(c) oxidation with potassium dichromate

(d) ozonolysis

(c) n-propyl alcohol and iso-propyl alcohol gives different products on oxidation with K2Cr2O7

CH3-CH2-CH2OHK2Cr2O7/H2SO4OCH3-CH2-CHO

  n-propyl alcohol                             Propionaldehyde

       1°alcohol

K2Cr2O7/H2SO4O

    Iso-propyl alcohol                       Acetone

         2°alcohol

Difficulty Level:

  • 20%
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  • 54%
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Among the following sets of reactants which one produces anisole?                           

(a) CH3CHO, RMgX

(b) C6H5OH, NaOH, CH3I

(c) C6H5OH, neutral FeCl3

(d) C6H5-CH3, CH3COCl, AlCl3

(b) Williamson's synthesis

Difficulty Level:

  • 13%
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Consider the following reaction,

EthanolPBr3Al.KOH Y (ii) H2O, heat(i) H2SO4, room temperatureZ                                

The product Z is

(a) CH2=CH2

(b) CH3CH2OCH2CH3

(c) CH3CH2OSO3H

(d) CH3CH2OH

(d)

 

Difficulty Level:

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In the following sequence of reactions,

CH3-BrKCNAH3O+BetherLiAlH4C

the end product C is 

(a) acetone                    (b) methane

(c) acetaldehyde            (d) ethyl alcohol

(d) CH3Br -KBrKCNMethyl bromide CH3CNH3O+ Ethane nitrite     A CH3COOHEtherLiAlH4 Ethanoic  acid    B CH3CH2OHEthanol    C

In the presence of LiAlH4 carboxylic acid reduce in alcohols, directly.

Difficulty Level:

  • 8%
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  • 55%

Which one is formed when sodium phenoxide is heated with ethyl iodide?              

(a) Phenetole

(b) Ethyl phenyl alcohol

(c) Phenol

(d) None of the above

(a) When sodium phenoxide (C6H5ONa) is heated with ethyl iodide (C2H5I) it forms ethyl phenyl ether which is also called phenetole. This reaction is called Williamson's synthesis.

 

Difficulty Level:

  • 35%
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Identity Z in the sequence of reactions,                                         

CH3CH2CH=CH2 HBr/H2O2YC2H5ONaZ

(a) CH3-(CH2)3-O-CH2CH3

(b) (CH3)2CH2-O-CH2CH3

(c) CH3(CH2)4-O-CH3

(d) CH3CH2-CH(CH3)-O-CH2CH3

(a) CH3CH2CH=CH2Anti-Markownikoff's ruleHBr/H2O2

      CH3CH2CH2CH2BrBromo-butane (1°  product)

      CH3CH2CH2CH2BrSN2 reactionC2H5ONaCH3CH2CH2CH2OC2H5  (williamson's synthesis)

Difficulty Level:

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Reaction of ethyl formate with excess of CH3MgI followed by hydrolysis gives

(1) n-propyl alcohol                  (2) ethanol              (3) isopropyl alcohol              (4)  propanal

 

(3) Ethyl formate on reaction with excess of CH3MgI, followed by hydrolysis gives a secondaty alcohol i.e. isopropyl alcohol.

Difficulty Level:

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Ethylene oxide when treated with Grignard reagent yields                                              

(a) secondary alcohol                                 (b) tertiary alcohol

(c) cyclopropyl alcohol                                (d) primary alcohol

(d) Ethylene oxide on treatment with Grignard reagent give additive product which undergo hydrolysis to give primary alcohol as final product

Difficulty Level:

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In a reaction, 

CH2=CH2acidHypochlorousMR

M=molecules, R=reagent. M and R are 

(a) CH3CH2Cl and NaOH

(b) CH2Cl. CH2OH and aq. NaHCO3

(c) CH3CH2OH and HCl

(d)  and heat

(b) CH2=CH2HOClNaHCO3(aq)R

So,M is and R is NaHCO3.

Difficulty Level:

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