Which is the least polar molecule?
Correct answer: B. HI
- A. HF
- B. HI
- C. HCl
- D. HBr
Explanation
To determine the polarity of diatomic molecules, we examine the difference in electronegativity between the two atoms. The smaller the difference, the less polar the molecule. In HI, the electronegativity of hydrogen is 2.2 and that of iodine is 2.66, giving an electronegativity difference of 0.46, which is the smallest among the given options. Therefore, HI is the least polar molecule. Conversely, HF has the largest electronegativity difference, making it the most polar, followed by HCl and HBr, which have intermediate differences.
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About Dipole Moment
Dipole moment measures the separation of positive and negative charge in a bond or molecule, with magnitude related to charge and distance, μ = q r. Questions distinguish polar bonds from polar molecules by considering bond direction, molecular geometry and whether individual bond moments cancel through symmetry.
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