Back to Directory
NEET CHEMISTRYMedium

Arrange the following species in increasing order of their dipole moments: NH3,NF3,BF3,H2ONH_3, NF_3, BF_3, H_2O

A

NH3<BF3<NF3<H2ONH_3 < BF_3 < NF_3 < H_2O

B

BF3<NF3<NH3<H2OBF_3 < NF_3 < NH_3 < H_2O

C

BF3<NH3<NF3<H2OBF_3 < NH_3 < NF_3 < H_2O

D

H2O<NF3<NH3<BF3H_2O < NF_3 < NH_3 < BF_3

Step-by-Step Solution

  1. Analyze BF3BF_3: Boron trifluoride has a trigonal planar geometry (sp2sp^2 hybridisation). Due to its symmetry, the individual bond dipoles cancel each other out completely.
  • μ=0\mu = 0.
  1. Analyze NF3NF_3 vs NH3NH_3: Both have a trigonal pyramidal structure with one lone pair on Nitrogen.
  • In NH3NH_3, the bond moments (N-H) point towards Nitrogen (N is more electronegative). The orbital dipole of the lone pair also points upwards. They reinforce each other (Vector addition).
  • In NF3NF_3, the bond moments (N-F) point towards Fluorine (F is more electronegative). The orbital dipole points upwards. They oppose each other (Vector subtraction).
  • Therefore, μ(NH3)>μ(NF3)\mu(NH_3) > \mu(NF_3).
  1. Analyze H2OH_2O: Water has a bent structure with two lone pairs on Oxygen. The large electronegativity difference between O and H, combined with the contribution of two lone pairs, results in the highest dipole moment among the group (\approx 1.85 D).
  2. Conclusion: The increasing order is BF3(0)<NF3<NH3<H2OBF_3 (0) < NF_3 < NH_3 < H_2O.
Practice Mode Available

Master this Topic on Sushrut

Join thousands of students and practice with AI-generated mock tests.

Get Started