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MHT CET Chemistry Chemical Bonding and Molecular Structure 2026 MHT CET 2026 (18 April Shift 2)

MHT CET Chemistry Question (2026) — Solution

Question

Select the incorrect statement from the following.

Options

  1. A. NH _3 and NF _3 both are polar molecules
  2. B. NH _3 and NF _3 both have pyramidal shape
  3. C. In NH _3 and NF _3 the orbital dipole due to lone pair is in the same direction as that of resultant dipole moment of other three bonds
  4. D. Dipole moment of NH _3 is greater than NF _3

Answer

C. In NH _3 and NF _3 the orbital dipole due to lone pair is in the same direction as that of resultant dipole moment of other three bonds

Step-by-step solution

Both NH _3 and NF _3 have a central nitrogen atom with sp^3 hybridization and one lone pair, giving them a trigonal pyramidal shape. Both are polar molecules. In NH _3, nitrogen is more electronegative than hydrogen. The bond dipole moments of the three N-H bonds are directed towards the nitrogen atom. Their resultant dipole moment is in the same direction as the orbital dipole due to the lone pair, leading to a higher net dipole moment. In NF _3, fluorine is more electronegative than nitrogen. The bond dipole moments of the three N-F bonds are directed towards the fluorine atoms. Their resultant dipole moment is in the opposite direction to the orbital dipole due to the lone pair. This partial cancellation results in a lower net dipole moment for NF _3 compared to NH _3. Therefore, the statement that the orbital dipole due to the lone pair is in the same direction as the resultant dipole moment of the three bonds in both molecules is incorrect.

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