JEE Main · 2024 · Shift-IIeasyBOND-011

The incorrect statement regarding ethyne is

Chemical Bonding · Class 11 · JEE Main Previous Year Question

Question

The incorrect statement regarding ethyne is

Options
  1. a

    The C–C bond in ethyne is shorter than that in ethene

  2. b

    Both carbons are sp hybridised

  3. c

    Ethyne is linear

  4. d

    The carbon–carbon bond in ethyne is weaker than that in ethene

Correct Answerd

The carbon–carbon bond in ethyne is weaker than that in ethene

Detailed Solution

🧠 In ethyne \ceHCCH\ce{HC≡CH}: both C are sp-hybridised, the molecule is linear, and the C≡C triple bond is shorter and stronger than C=C. Statement (d) reverses the strength comparison — that is the error.

| Statement | Correct? | |---|---| | (a) C–C bond shorter than in ethene | ✓ (triple bond length ~120 pm vs ~134 pm) | | (b) Both C are sp hybridised | ✓ | | (c) Ethyne is linear | ✓ | | (d) C–C bond weaker than in ethene | ✗ — triple bond (~835 kJ/mol) is stronger than double bond (~611 kJ/mol) |

⚠️ Trap: "more bonds = shorter = stronger" — all three properties move together. A shorter bond is always stronger (for bonds between the same pair of atoms).

Answer: (d)\boxed{\text{Answer: (d)}}

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