Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Alcohols Phenols and Ethers question

2022 · 25 Jul · Shift 1 · Q11
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Chemistry
  4. /Alcohols Phenols and Ethers
  5. /2022 · 25 Jul · Shift 1 · Q11

Alcohols Phenols and Ethers question

2022 · 25 Jul · Shift 1 · Q11

JEE MainChemistryAlcohols Phenols and EthersMCQ+4 / −1
Given below are two statements : Statement I : On heating with KHSO4\mathrm{KHSO}_{4}KHSO4​, glycerol is dehydrated and acrolein is formed. Statement II : Acrolein has fruity odour and can be used to test glycerol's presence. Choose the correct option.
  1. A
    Both Statement I and Statement II are correct.
  2. B
    Both Statement I and Statement II are incorrect.
  3. C
    Statement I is correct but Statement II is incorrect.
  4. D
    Statement I is incorrect but Statement II is correct.
View written solutionFree

Correct answer: C

  1. Check Statement I

Glycerol is a trihydric alcohol: HO−CH2−CH(OH)−CH2OH\mathrm{HO{-}CH_2{-}CH(OH){-}CH_2OH}HO−CH2​−CH(OH)−CH2​OH

On heating glycerol with a dehydrating agent like KHSO4\mathrm{KHSO_4}KHSO4​, it undergoes dehydration to form acrolein (propenal): CH2OH−CHOH−CH2OH→ΔKHSO4CH2=CH−CHO+2H2O\mathrm{CH_2OH{-}CHOH{-}CH_2OH \xrightarrow[\Delta]{KHSO_4} CH_2{=}CH{-}CHO + 2H_2O}CH2​OH−CHOH−CH2​OHKHSO4​Δ​CH2​=CH−CHO+2H2​O

So, Statement I is correct.

  1. Check Statement II

Acrolein (CH2=CH−CHO\mathrm{CH_2{=}CH{-}CHO}CH2​=CH−CHO) has a sharp, pungent, irritating odour, not a fruity odour.

  • Fruity odour is generally associated with esters.
  • The formation of acrolein with its irritating smell is indeed used as a test for glycerol.

Thus Statement II says:

  • acrolein has fruity odour ❌
  • can be used to test glycerol's presence ✅

Since the statement as a whole contains a wrong part, Statement II is incorrect.

  1. Conclusion
  • Statement I: Correct
  • Statement II: Incorrect

Therefore, the correct option is: C\boxed{\text{C}}C​

PreviousNext

More from Alcohols Phenols and Ethers

  • Most stable product of the following reaction is: Includes diagram2022 · MCQ
  • The intermediate X, in the reaction : Includes diagram2022 · MCQ
  • In the following reaction : The compounds A and B respectively are : Includes diagram2022 · MCQ
  • In the given reaction 'A' can be Includes diagram2022 · MCQ
  • The major product formed in the following reaction, is Includes diagram2022 · MCQ
  • Which reactant will give the following alcohol on reaction with one mole of phenyl magnesium bromide (PhMgBr) followed by acidic hydrolysis? Includes diagram2022 · MCQ
  • The major product of the following reaction is Includes diagram2022 · MCQ
  • The difference in the reaction of phenol with bromine in chloroform and bromine in water medium is due to :2022 · MCQ