Which of the following molecules has highest dipole moment? — Chemical Bonding Chemistry Question

💡 Solution & Explanation

Step 1: Symmetrical molecules like BF_3 (trigonal planar) and B_2H_6 (symmetrical bridged structure) have a net dipole moment of zero. Step 2: Compare NH_3 and NF_3, which are both pyramidal. In NH_3, the highly polar N-H bond dipoles point toward Nitrogen, reinforcing the direction of the lone pair dipole. In NF_3, the highly electronegative Fluorine atoms pull electron density away from Nitrogen, meaning the N-F bond dipoles oppose and partially cancel the lone pair dipole. Step 3: As a result, the net dipole moment of NH_3 is significantly larger than that of NF_3. Thus, the correct option is (b).