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

Basics of Organic Chemistry question

2023 · 8 Apr · Shift 2 · Q12
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. /Basics of Organic Chemistry
  5. /2023 · 8 Apr · Shift 2 · Q12

Basics of Organic Chemistry question

2023 · 8 Apr · Shift 2 · Q12

JEE MainChemistryBasics of Organic ChemistryMCQ+4 / −1
The descending order of acidity for the following carboxylic acid is- A. CH3COOH\mathrm{CH}_{3} \mathrm{COOH}CH3​COOH B. F3C−COOH\mathrm{F}_{3} \mathrm{C}-\mathrm{COOH}F3​C−COOH C. ClCH2−COOH\mathrm{ClCH}_{2}-\mathrm{COOH}ClCH2​−COOH D. FCH2−COOH\mathrm{FCH}_{2}-\mathrm{COOH}FCH2​−COOH E. BrCH2−COOH\mathrm{BrCH}_{2}-\mathrm{COOH}BrCH2​−COOH Choose the correct answer from the options given below:
  1. A
    B > C > D > E > A
  2. B
    D > B > A > E > C
  3. C
    B > D > C > E > A
  4. D
    E > D > B > A > C
View written solutionFree

Correct answer: C

  1. Principle involved: Inductive effect

For carboxylic acids, acidity depends on the stability of the conjugate base, RCOO−\mathrm{RCOO^-}RCOO−.

  • Electron-withdrawing groups (−I-I−I effect) increase acidity by stabilizing the carboxylate ion.
  • Electron-donating groups decrease acidity.

So, among substituted acetic acids, stronger −I-I−I effect on the α\alphaα-carbon gives stronger acid.


  1. Given acids
  • A=CH3COOHA = \mathrm{CH_3COOH}A=CH3​COOH (acetic acid)
  • B=CF3COOHB = \mathrm{CF_3COOH}B=CF3​COOH (trifluoroacetic acid)
  • C=ClCH2COOHC = \mathrm{ClCH_2COOH}C=ClCH2​COOH (chloroacetic acid)
  • D=FCH2COOHD = \mathrm{FCH_2COOH}D=FCH2​COOH (fluoroacetic acid)
  • E=BrCH2COOHE = \mathrm{BrCH_2COOH}E=BrCH2​COOH (bromoacetic acid)

  1. Compare electron-withdrawing power

For halogens, the −I-I−I effect follows:

F>Cl>Br\mathrm{F > Cl > Br}F>Cl>Br

Also, three fluorine atoms withdraw much more strongly than one fluorine atom. Therefore:

CF3COOH>FCH2COOH\mathrm{CF_3COOH} > \mathrm{FCH_2COOH}CF3​COOH>FCH2​COOH

And among mono-haloacetic acids:

FCH2COOH>ClCH2COOH>BrCH2COOH\mathrm{FCH_2COOH} > \mathrm{ClCH_2COOH} > \mathrm{BrCH_2COOH}FCH2​COOH>ClCH2​COOH>BrCH2​COOH

Finally, unsubstituted acetic acid is the weakest because CH3\mathrm{CH_3}CH3​ has a +I+I+I effect:

BrCH2COOH>CH3COOH\mathrm{BrCH_2COOH} > \mathrm{CH_3COOH}BrCH2​COOH>CH3​COOH


  1. Overall descending order of acidity

Combining all comparisons:

CF3COOH>FCH2COOH>ClCH2COOH>BrCH2COOH>CH3COOH\mathrm{CF_3COOH > FCH_2COOH > ClCH_2COOH > BrCH_2COOH > CH_3COOH}CF3​COOH>FCH2​COOH>ClCH2​COOH>BrCH2​COOH>CH3​COOH

In terms of labels:

B>D>C>E>AB > D > C > E > AB>D>C>E>A


  1. Match with options

Option C gives:

B>D>C>E>AB > D > C > E > AB>D>C>E>A

So, the correct option is C.


  1. Comparison with stored answer

Stored correct answer = C.

My derived answer = C.

Hence, they agree.

PreviousNext

More from Basics of Organic Chemistry

  • The correct IUPAC nomenclature for the following compound is: Includes diagram2023 · MCQ
  • Using column chromatography, mixture of two compounds 'A' and 'B' was separated. 'A' eluted first, this indicates 'B' has2023 · MCQ
  • The decreasing order of hydride affinity for following carbocations is: Choose the correct answer from the options given below: Includes diagram2023 · MCQ
  • Thin layer chromatography of a mixture shows the following observation: The correct order of elution in the silica gel column chromatography is Includes diagram2023 · MCQ
  • Three organic compounds A, B and C were allowed to run in thin layer chromatography using hexane and gave the following result (see figure). The Rf​ value of the most polar compound is ​… Includes diagram2023 · Numerical
  • Among the following compounds, the one which shows highest dipole moment is2023 · MCQ
  • Given below are two statements : Statement I : Tropolone is an aromatic compound and has 8π electrons. Statement II : π electrons of >C=O group in tropolone is involved in aromaticity. In the light of the…2023 · MCQ
  • Which of the following statement is correct for paper chromatography?2023 · MCQ