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Aldehydes, Ketones and Carboxylic Acids

JEE Main 2024 (Online) 29th January Morning ShiftNumericalEasy📈 Topic in 12% papers+4
Ques. 1JEE Main 2024, 29 January (Morning Shift)

From the compounds given below, number of compounds which give positive Fehling's test is . Benzaldehyde, Acetaldehyde, Acetone, Acetophenone, Methanal, 4-nitrobenzaldehyde, cyclohexane carbaldehyde.

Answer

3

Solution

Fehling's test ( Cu2+ → red Cu2O) is given by aliphatic aldehydes only

Positive: acetaldehyde (CH3CHO), methanal (HCHO), cyclohexane carbaldehyde ( C6H11CHO, –CHO on an sp3 carbon) ⇒ 3

Negative: benzaldehyde, 4-nitrobenzaldehyde (aromatic aldehydes); acetone, acetophenone (ketones)

Answer: 3

Keep practising — Aldehydes, Ketones and Carboxylic Acids

Ques. 2JEE Main 2024, 29 January (Evening Shift)

Identify the reagents used for the following conversion [figure]

  1. A = LiAlH4, B = NaOH(aq), C = NH2-NH2/KOH, ethylene glycol
  2. A = DIBAL-H, B = NaOH(aq), C = NH2-NH2/KOH, ethylene glycol
  3. A = LiAlH4, B = NaOH(alc), C = Zn/HCl
  4. A = DIBAL-H, B = NaOH(alc), C = Zn/HCl
Ques. 3JEE Main 2024 (Online)

Match List-I with List-II and choose the correct option.

  1. A-II, B-IV, C-I, D-III
  2. A-I, B-II, C-III, D-IV
  3. A-IV, B-III, C-II, D-I
  4. A-II, B-I, C-IV, D-III

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