Question

Arrange in the order of dipole moment: \[ \text{NH}_3, \, \text{NF}_3, \, \text{H}_2\text{S}, \, \text{CHCl}_2 \]

• A. NH$_3$ $>$ NF$_3$ $>$ H$_2$S $>$ CHCl$_2$
• B. NF$_3$ $>$ NH$_3$ $>$ CHCl$_2$ $>$ H$_2$S
• C. NH$_3$ $>$ H$_2$S $>$ CHCl$_2$ $>$ NF$_3$
• D. CHCl$_2$ $>$ H$_2$S $>$ NF$_3$ $>$ NH$_3$

Hint:

To compare dipole moments, consider the shape of the molecule and the electronegativity differences between atoms. More electronegative atoms and asymmetrical shapes typically result in larger dipole moments.

Answer 1

The Correct Option is A

The dipole moment of a molecule depends on the difference in electronegativity between atoms and the molecular geometry.

1. Step 1: Analyze each molecule's dipole moment. - NH$_3$ (Ammonia): This molecule has a pyramidal shape due to the lone pair on nitrogen, with a significant dipole moment because nitrogen is highly electronegative and the lone pair pushes the bond pairs. - NF$_3$ (Nitrogen trifluoride): Although it has a similar structure to NH$_3$, the dipole moment of NF$_3$ is lower because fluorine is highly electronegative, but the molecule has a more symmetrical shape that partially cancels the dipole. - H$_2$S (Hydrogen sulfide): The molecule has a bent shape, but sulfur’s electronegativity is lower than oxygen, and thus the dipole moment is smaller than that of NH$_3$. - CHCl$_2$ (Dichloromethane): This molecule has a tetrahedral shape and chlorine is highly electronegative, which would result in a moderate dipole moment. However, the dipole moment is lower than that of NH$_3$ and NF$_3$ because the structure of CHCl$_2$ is more symmetric. Thus, the correct order of dipole moments is NH$_3$ > NF$_3$ > H$_2$S > CHCl$_2$.