NEET 2022 Chemistry Diborane MCQ Question

Chapter: The p-Block Elements

Class: 11 Topic: Structure and bonding in Diborane $(B_2H_6)$ Difficulty: 🟡 Moderate

✅ Ans: Both the Boron atoms are $sp^2$ hybridised

Diborane has the structure:

$$B_2H_6$$

It contains:

• 4 terminal B–H bonds → normal 2-centre–2-electron (2c–2e) bonds.
• 2 bridging H atoms → each forms a 3-centre–2-electron (3c–2e) bond with the two B atoms.

Each boron is approximately $sp^3$ hybridised, not $sp^2$.

Therefore, the statement “Both the Boron atoms are $sp^2$ hybridised” is incorrect.

❌ Why other options are correct?

• (1) 4 terminal B–H bonds are 2c–2e bonds → ✅
• (2) Four terminal H atoms and two B atoms lie approximately in one plane → ✅
• (4) Diborane has two 3c–2e bridge bonds → ✅

📌 NCERT: Diborane is electron-deficient and contains two B–H–B three-centre-two-electron bonds.

🧠 NEET Trick: Diborane = 4 terminal 2c–2e bonds + 2 bridge 3c–2e bonds; B is $sp^3$.