Question

The dipole moments of diatomic molecules AB and CD are
10.41D and 10.27 D, respectively while their bond distances
are 2.82 and 2.67 Å, respectively. This indicates that
(a) bonding is 100% ionic in both the molecules
(b) AB has more ionic bond character than CD
(c) AB has lesser ionic bond character than CD
(d) bonding is nearly covalent in both the molecules

Answer 1

$\huge{\bold{\red{\star{\pink{Heya !}}}}}$

Option [C] is the answer ✔️

Answer 2

The dipole moment is defined as the product of magnitude of the two charges and the distance between them.

    Dipole moment = Magnitude of charge * Distance between them

• Now, the relation between ionic charachter, dipole moment, and bond lenghts is as follows:                                                                               Percentage ionic charachter =( Observed dipole moment/Calculated dipole moment) *100
• Observed dipole moment = Given data in the question.
• Calculated dipole moment for AB is as follows:                                                          Dipole moment of  AB = (1.6*$10^{-19$ C) ( 2.82*$10^{-10}$ m) (1 D/3.36*$10^{-30}$ Cm)        =    13.42 D
• Therefore % ionic charachter of AB =  (10.41 D/13.42 D) * 100                           =  77.57 %
• Now, Dipole moment for CD = (1.6*$10^{-19$ C)( 2.67*$10^{-10}$ m) (1 D/3.36*$10^{-30}$Cm)        = 12.71 D

• Therefore % ionic charachter of CD = ( 10.27 D/12.71 D) * 100                       =80.80 %
• Therefore CD is more ionic than AB.  

• c) AB has lesser ionic bond character than CD.