MCQMediumJEE 2025Diazonium Salts & Reactions

JEE Chemistry 2025 Question with Solution

Consider the following reactions: NH2ONaNO2,HCl,05C[A]HCl dil., NaOH[B]NH_2O \xrightarrow{NaNO_2, HCl, 0-5^\circ C} [A] \xrightarrow{HCl\ \text{dil.},\ NaOH} [B]

  • (i) The molecular formula of [A] is C₁₄H₁₄N₂O₂

  • (ii) The molecular formula of [C] is C₁₆H₁₈N₂O₂

The total number of sp³ hybridized carbon atoms in the major product [C] formed is _____.

  • A

    22

  • B

    33

  • C

    44

  • D

    55

Answer

Correct answer:C

Step-by-step solution

Standard Method

Given: The reaction sequence involves diazotization conditions with NaNO2NaNO_2 and HClHCl at 05C0-5^\circ C. The molecular formula of [A] is C₁₄H₁₄N₂O₂ and the molecular formula of [C] is C₁₆H₁₈N₂O₂.

Find: The total number of sp³ hybridized carbon atoms in the major product [C].

The extracted solution states that the final major product [C] contains 4 sp³ hybridized carbon atoms.

The solution approach is based on counting carbons connected through single bonds in the final product structure. From the molecular understanding described in the solution, the total number of sp³ hybridized carbons in [C] is 4.

Therefore, the correct option is C.

Extracted Approach Summary

Given: The sequence starts with diazotization and subsequent conversion steps.

Find: Number of sp³ carbons in major product [C].

The solution describes:

  1. Reaction Analysis: the sequence suggests diazotization of an amine-containing substrate.
  2. Structure Clue from [A]: [A] has formula C₁₄H₁₄N₂O₂.
  3. Final Product Clue: [C] has formula C₁₆H₁₈N₂O₂.
  4. Hybridization Count: the final structure is interpreted to contain 4 carbons with sp³ hybridization.

Thus, the total number of sp³ hybridized carbon atoms in [C] is 4, so the correct option is C.

Note: The solution gives the final count directly but does not supply a fully explicit structural derivation for [C].

Common mistakes

  • Counting all carbon atoms attached to heteroatoms as sp³ without checking whether they are part of an aromatic or unsaturated system is incorrect. Hybridization must be assigned from bonding, not from the attached atom. Count only tetrahedral carbon atoms in the final product structure.

  • Using the intermediate [A] or [B] to count sp³ carbons instead of the major product [C] gives the wrong answer. The question explicitly asks for the number in [C], so the count must be done only for the final product.

  • Confusing molecular formula information with direct hybridization count is a conceptual error. A formula such as C₁₆H₁₈N₂O₂ does not by itself identify which carbons are sp³; the final structure or the stated solution conclusion must be used.

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