Question

Of the following molecules, the one, which has permanent dipole moment, is:
(1) SiF₄ (2) BF₃ (3) PF₃ (4) PF₅

Answer 1

Symmetrical structure has zero dipole moment.
SiF₄ - tetrahedral - symmetrical structure - Zero dipole moment
BF₃ - Trigonal planar - Symmetrical structure - Zero dipole moment
PF₃ - pyramidal shape - Non symmetrical structure - Has dipole moment.
PF₅ - Trigonal bipyramidal - symmetrical structure - Zero dipole moment