Question

Identify the set of molecules which are not in the correct order of their dipole moments.

• A. \( HF > HCl > HBr \)
• B. \( H_2O > H_2S > CO_2 \)
• C. \( H_2S > HCl > HF \)
• D. \( NH_3 > NF_3 > BF_3 \)
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Hint:

Dipole moment increases with electronegativity differences and decreases with symmetry in molecules.

Answer 1

The Correct Option is C

Step 1: Understanding Dipole Moments
Dipole moment is influenced by electronegativity and molecular shape.
- The dipole moment is directly proportional to the charge difference and bond length. Step 2: Examining the Given Orders - (1) \( HF>HCl>HBr \):
- Correct, as fluorine (F) is the most electronegative, so HF has the highest dipole moment.
- (2) \( H_2O>H_2S>CO_2 \):
- Correct, as \( H_2O \) has strong hydrogen bonding, and \( CO_2 \) is linear (zero dipole moment).
- (3) \( H_2S>HCl>HF \):
- Incorrect! Correct order should be: HF>HCl>H_2S because HF has the strongest dipole moment due to high electronegativity.
- (4) \( NH_3>NF_3>BF_3 \):
- Correct, \( NH_3 \) has a high dipole moment due to its lone pair, while \( BF_3 \) is nonpolar. Thus, the incorrect set is \( H_2S>HCl>HF \). \bigskip