Question

Which of the following hybrides electron deficient?

• A. $\text{CH}_4$
• B. NaH
• C. $\text{B}_2\text{H}_4$
• D. $\text{CaH}_2$

Answer 1

The Correct Option is C

The term "electron-deficient" refers to a compound that lacks sufficient valence electrons to form conventional covalent bonds. Based on this definition, the electron-deficient compound among the options provided is:
(C) B₂H₄: Diborane (B₂H₄) is an example of an electron-deficient compound. It exhibits a bridged structure with boron atoms sharing electrons but not forming enough conventional covalent bonds to satisfy the octet rule. Diborane is known for its electron-deficient nature and its ability to undergo unique reactions due to the presence of vacant bonding orbitals.
The other options,
(A) CH₄ (methane), 
(B) NaH (sodium hydride), and
(D) CaH₂ (calcium hydride), do not exhibit electron-deficient characteristics as they follow conventional covalent bonding patterns and possess sufficient valence electrons to satisfy the octet rule.
Therefore, the correct answer is (C) B₂H₄.

Answer 2

Correct Answer: B₂H₄ 

Explanation:
Diborane (B₂H₄) is an electron-deficient compound. Each boron atom has only 3 valence electrons, and forming normal 2-center 2-electron bonds with hydrogen doesn’t complete their octet.

Instead, diborane forms unusual 3-center 2-electron bonds (banana bonds) between boron and hydrogen atoms. This is a clear sign of electron deficiency.

Other options:

• CH₄ – Methane is a stable, electron-sufficient molecule.
• NaH – Sodium hydride is an ionic compound, not electron deficient.
• CaH₂ – Calcium hydride is also ionic and not electron deficient.