JEE MainChemistryChemical Bonding and Molecular StructureMCQ+4 / −1
A central atom in a molecule has two lone pairs of electrons and forms three single bonds. The shape of this molecule is :
- Atrigonal pyramidal
- BT-shaped
- Csee-saw
- Dplanar triangular
View written solutionFree
Correct answer: B
-
Count the electron pairs around the central atom
The central atom has:
- 3 single bonds bond pairs
- 2 lone pairs lone pairs
So, total electron pairs around the central atom:
-
Determine the electron-pair geometry
For 5 electron pairs, according to VSEPR theory, the electron-pair geometry is:
-
Place the lone pairs in the most stable positions
In a trigonal bipyramidal arrangement, lone pairs prefer equatorial positions because these positions have fewer interactions.
Since there are 2 lone pairs, both occupy equatorial positions.
-
Find the molecular shape
After placing 2 lone pairs equatorially, the 3 bonded atoms occupy:
- 2 axial positions
- 1 equatorial position
This gives the molecular shape:
-
Check the options
- A: trigonal pyramidal corresponds to , not correct
- B: T-shaped corresponds to , correct
- C: see-saw corresponds to , not correct
- D: planar triangular corresponds to , not correct
-
Final answer
The molecule has the type: Hence its shape is:
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