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But-2-yne and hydrogen (one mole each) are separately treated with (i) Pd / C and (ii) Na / liq . NH ₃ to give the products X and Y respectively. Identify the incorrect statements. A. X and Y are stereoisomers. B. Dipole moment of X is zero. C. Boiling point of X is higher than Y . D. X and Y react with O ₃ / Zn + H ₂ O to give different products. Choose the correct answer from the options given below :

Options

  1. AB and D Only
  2. BA and C Only
  3. CA and B Only
  4. DB and C Only

Correct answer

A. B and D Only

Step-by-step solution

But-2-yne ( CH₃-C C-CH₃ ) undergoes partial hydrogenation. Reaction with Pd/C (Lindlar-like conditions for 1 mole H₂ ) gives cis-but-2-ene as product X . Reaction with Na/liq. NH₃ (Birch reduction) gives trans-but-2-ene as product Y . Statement A: X (cis) and Y (trans) are geometrical isomers, hence stereoisomers. This is correct. Statement B: Cis-but-2-ene ( X ) has a non-zero dipole moment ( 0 ) due to the additive nature of bond moments, while trans-but-2-ene ( Y ) has zero dipole moment ( = 0 ) due to symmetry.

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