Which of the following would have a permanent dipole moment ?

A permanent dipole moment arises when there is a separation of charge within a molecule, resulting in a molecule with a slightly positive charge on one side and a slightly negative charge on the other. To determine which of the given molecules has a permanent dipole moment, we need to consider their molecular geometry. BF3 has a trigonal planar geometry, which is symmetrical, and therefore it does not have a permanent dipole moment. SiF4 has a tetrahedral geometry, which is also symmetrical, and it does not have a permanent dipole moment. XeF4 has a square planar geometry, which is symmetrical, and it does not have a permanent dipole moment. SF4, on the other hand, has a seesaw geometry, which is asymmetrical, resulting in a permanent dipole moment. Therefore, the correct answer is option (C) SF4. Notice that the molecular geometry of a molecule plays a crucial role in determining its dipole moment.