Question

Pick up the correct statement.

• A. Dipole moment of ammonia is due to orbital dipole and resultant dipole in same direction.
• B. O\(_2\), H\(_2\) shown bond dipole due to polarisation.
• C. Dipole moment is scalar quantity.
• D. In BF\(_3\), bond dipoles are zero but dipole moment is higher.

Hint:

In molecules with lone pairs, the resultant dipole moment can be influenced by the orientation of the bonds and lone pairs.

Answer 1

The Correct Option is A

To determine the correct statement, let's examine each option:

1. Dipole moment of ammonia is due to orbital dipole and resultant dipole in same direction.

   Ammonia (NH₃) has a trigonal pyramidal molecular geometry, which leads to a net dipole moment. In this molecule, the lone pair of electrons on nitrogen creates an orbital dipole, and the bond dipoles from the N-H bonds point towards the nitrogen, aligning with the orbital dipole. Hence, the resultant dipole is significant and points in the same general direction as the orbital dipole.

2. O₂, H₂ show bond dipole due to polarisation.

   Both O₂ and H₂ are homonuclear diatomic molecules with nonpolar covalent bonds. Since atoms of the same element share electrons equally, no bond dipole or polarization exists.

3. Dipole moment is scalar quantity.

   Dipole moment is a vector quantity, not scalar. It has both magnitude and direction.

4. In BF₃, bond dipoles are zero but dipole moment is higher.

   Boron trifluoride (BF₃) has a trigonal planar structure. Although each B-F bond has a polarity, the symmetrical arrangement causes the bond dipoles to cancel out, resulting in a net dipole moment of zero.

Thus, the correct statement is: Dipole moment of ammonia is due to orbital dipole and resultant dipole in same direction.

Answer 2

To determine the correct statement among the given options, we need to analyze the concept of dipole moment and its formation in different molecules:

• Dipole moment of ammonia is due to orbital dipole and resultant dipole in same direction. Ammonia (NH₃) is a polar molecule. The nitrogen atom is more electronegative than hydrogen atoms, creating a net dipole moment due to both orbital and the molecular geometry. The lone pair on the nitrogen adds to the polarity, aligning the orbital dipole and the resultant dipole in the same direction.
• O₂, H₂ show bond dipole due to polarization. Both O₂ and H₂ are diatomic molecules with identical atoms, leading to a nonpolar nature. They do not exhibit bond dipoles due to polarization as both bonds involve identical electronegativity.
• Dipole moment is scalar quantity. Dipole moment is a vector quantity, not scalar, as it has both magnitude and direction.
• In BF₃, bond dipoles are zero but dipole moment is higher. BF₃ is a trigonal planar molecule where bond dipoles do exist but cancel each other, resulting in a zero net dipole moment, not higher.

The correct statement is: Dipole moment of ammonia is due to orbital dipole and resultant dipole in same direction.