Which of the following would have a permanent dipole moment?

Which of the following would have a permanent dipole moment?
  1. $\mathrm{SiF}_4$
  2. $\mathrm{SF}_4$
  3. $\mathrm{XeF}_4$
  4. $\mathrm{BF}_3$

Solution

Permanent dipoles occur when two atoms in moleculehave substantially different electronegativity: One atom attracts electrons more than another, becoming more negative, while the other atom becomes more positive. A molecule with a permanent dipole moment is called a polar molecule.

Asked in: NEET 2005

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