Number of electron deficient molecules among the following PH3,\ B2H6,\ CCl4,\ NH3, LiH and BCl3 is
Chemical Bonding · Class 11 · JEE Main Previous Year Question
Number of electron deficient molecules among the following , LiH and is
- a
0
- b
1
- c✓
2
- d
3
2
🧠 Electron-deficient molecules have a central atom with fewer than 8 electrons after normal covalent bonding. Group 13 elements (B, Al) with 3 bonds and no lone pair are the classic case.
- : P has 3 bonds + 1 LP = 8e → satisfied ✗
- : Each B has only 3 two-electron bonds (6e around B) in the conventional Lewis sense. Even with 3c–2e bridging bonds, B starts electron-deficient. ✓
- : C has 4 bonds = 8e → satisfied ✗
- : N has 3 bonds + 1 LP = 8e → satisfied ✗
- LiH: ionic compound; not classified as a covalent electron-deficient molecule ✗
- : B has 3 bonds = 6e → electron-deficient ✓
⚠️ Trap: LiH is ionic, not covalently electron-deficient. satisfies the octet with its lone pair — do not confuse lone pair with electron deficiency.
Practice this question with progress tracking
Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Chemical Bonding) inside The Crucible, our adaptive practice platform.
More JEE Main Chemical Bonding PYQs
The number of species from the following that have pyramidal geometry around the central atom is ____ {S_2O_3^{2-},\ SO_4^{2-},\ SO_3^{2-},\ S_2O_7^{2-}}
Order of covalent bond — which of the following are correct? A. KF KI; LiF KF B. KF < KI; LiF KF C. SnCl4 SnCl2; CuCl NaCl D. LiF KF; CuCl NaCl E. KF < KI; CuCl NaCl
Given below are two statements: Statement I: SbCl5 is more covalent than SbCl3. Statement II: The higher oxides of halogens also tend to be more stable than the lower ones. Choose the most…
Which of the following pair of molecules contain an odd electron molecule and an expanded octet molecule?
Identify the species having one π-bond and maximum number of canonical forms from the following: