Which of the following species has a bond angle of 120∘?
A
SF6
B
NCl3
C
BCl3
D
PH3
Step-by-Step Solution
Analyze BCl3: The central Boron atom has 3 valence electrons. It forms 3 sigma bonds with Chlorine atoms and has zero lone pairs. According to VSEPR theory, a molecule with 3 bond pairs and 0 lone pairs (AB3 type) adopts a trigonal planar geometry. The hybridisation is sp2 and the bond angle is exactly 120∘ .
Analyze other options:
SF6: Sulphur is sp3d2 hybridised with octahedral geometry. Bond angles are 90∘ .
NCl3: Nitrogen is sp3 hybridised with 1 lone pair (Pyramidal geometry). Bond angle is less than 109.5∘ .
PH3: Phosphorus is sp3 hybridised (or unhybridised per Drago's rule) with 1 lone pair. Bond angle is close to 93∘ (Pyramidal) .
Conclusion: Only BCl3 has a bond angle of 120∘.
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