JEE Main · 2021 · Shift-ImediumPB11-032

The incorrect statement about B2H6 is:

p-Block Elements (Class 11) · Class 11 · JEE Main Previous Year Question

Question

The incorrect statement about B2H6\mathrm{B_2H_6} is:

Options
  1. a

    All B–H–B angles are of 120°120°

  2. b

    The two B–H–B bonds (bridged and terminal) are not of same length.

  3. c

    Terminal B–H bonds have less p-character when compared to bridging bonds.

  4. d

    Its fragment, BH3\mathrm{BH_3}, behaves as a Lewis acid.

Correct Answera

All B–H–B angles are of 120°120°

Detailed Solution

Strategy: Identify the incorrect statement about \ceB2H6\ce{B2H6} (diborane).

Step 1: Analysing Each Option

  • (A) "All B–H–B angles are 120°": ❌ Incorrect. The B–H–B bridge bond angles in diborane are approximately 83–84°, not 120°. The H–B–H angles for terminal bonds are ~121°, and the B–H–B bridge angles are narrowed by the geometry of the bridge. Angles of 120° would imply sp2sp^2 hybridisation which is incorrect.

  • (B) "Bridge and terminal B–H bonds differ in length": ✅ Correct. Terminal B–H ≈ 119 pm; bridge B–H ≈ 133 pm (longer, weaker 3c-2e bonds).

  • (C) "Terminal B–H bonds have less p-character than bridging": ✅ Correct. Terminal B–H bonds are in sp3sp^3 orbitals with ~25% s-character; bridge bonds involve more p-character.

  • (D) "\ceBH3\ce{BH3} behaves as Lewis acid": ✅ Correct. BH₃ is electron-deficient.

Answer: (A) All B–H–B angles are 120°\boxed{\text{Answer: (A) All B–H–B angles are 120°}}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from p-Block Elements (Class 11)) inside The Crucible, our adaptive practice platform.

The incorrect statement about B2H6 is: (JEE Main 2021) | Canvas Classes