Arrange the following molecules in increasing order of their dipole moment: BF ₃, NF ₃, NH ₃ and H ₂ O .

Step-by-step solution

BF ₃ has a trigonal planar geometry which is highly symmetrical, resulting in a net dipole moment of zero. Both NF ₃ and NH ₃ have a pyramidal geometry with one lone pair. In NH ₃ , the orbital dipole due to the lone pair is in the same direction as the resultant dipole moment of the three N-H bonds, leading to a higher net dipole moment. In NF ₃ , the orbital dipole is in the direction opposite to the resultant dipole moment of the three N-F bonds, which partially cancel each other, resulting in a very low dipole