JEE Main · 2020 · Shift-IhardHC-193

Consider the following reactions: {({C7H14})}{{'A'}} {{ozonolysis}} {'B'} + {'C'}

Hydrocarbons · Class 11 · JEE Main Previous Year Question

Question

Consider the following reactions: ’A’(\ceC7H14)ozonolysis’B’+’C’\underset{(\ce{C7H14})}{\text{'A'}} \xrightarrow{\text{ozonolysis}} \text{'B'} + \text{'C'} image

Options
  1. a

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  2. b

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  3. c

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  4. d

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Correct Answerd

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Detailed Solution

A has molecular formula \ceC7H14\ce{C7H14} (MW = 98), which means DoU = 1 (one double bond). Ozonolysis gives B + C. The tests applied to B and C are:

  • B gives iodoform test (positive) → B contains \ceCOCH3\ce{-CO-CH3} group (methyl ketone or acetaldehyde)
  • C gives silver mirror test (positive) → C is an aldehyde

Step 2: Identify B and C From the reactions shown:

  • B gives iodoform → B is a methyl ketone: \ceCH3COR\ce{CH3-CO-R}
  • C gives silver mirror → C is an aldehyde: \ceRCHO\ce{R'-CHO}

For \ceC7H14\ce{C7H14} with 1 double bond: B + C must together have 7 carbons. image This is 3-methylhex-3-ene → molecular formula \ceC7H14\ce{C7H14}

Answer: Option (d)

Key Points to Remember:

  • Iodoform test: detects \ceCH3CO\ce{CH3CO-} group (methyl ketones + ethanal)
  • Silver mirror test: detects aldehydes (\ceCHO\ce{-CHO})
  • Reconstruct alkene by replacing \ceC=O\ce{C=O} of both fragments with \ceC=C\ce{C=C}

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Consider the following reactions: {({C7H14})}{{'A'}} {{ozonolysis}} {'B'} + {'C'} (JEE Main 2020) | Canvas Classes