Question

The correct increasing order of dipole moment of the following molecules is

• A. $\mathrm{NF_3 < CHCl_3 < NH_3 < H_2O}$
• B. $\mathrm{NF_3 < CHCl_3 < H_2O < NH_3}$
• C. $\mathrm{H_2O < NF_3 < CHCl_3 < NH_3}$
• D. $\mathrm{CHCl_3 < NF_3 < H_2O < NH_3}$
• E. $\mathrm{NH_3 < NF_3 < CHCl_3 < H_2O}$

Hint:

Dipole moment tips: - Symmetry reduces dipole moment - Bent and pyramidal shapes give higher dipole moment

Answer 1

The Correct Option is A

Concept: Dipole moment depends on molecular geometry and vector addition of bond dipoles.

Step 1: Analyze each molecule.

• $\mathrm{NF_3}$: dipoles partially cancel $\Rightarrow$ very small dipole moment
• $\mathrm{CHCl_3}$: asymmetric tetrahedral $\Rightarrow$ moderate dipole moment
• $\mathrm{NH_3}$: trigonal pyramidal $\Rightarrow$ higher dipole moment
• $\mathrm{H_2O}$: bent structure $\Rightarrow$ highest dipole moment

Step 2: Arrange in increasing order.
\[ \mathrm{NF_3 < CHCl_3 < NH_3 < H_2O} \]