Question

Which of the following types of molecules always has a dipole moment? Linear molecules with two identical bonds. Trigonal pyramid molecules (three identical bonds). Trigonal planar molecules (three identical bonds equally spaced). Tetrahedral molecules (four identical bonds equally spaced). None has a dipole moment.

Answer 1

Answer:

Trigonal pyramid molecules (three identical bonds)

Explanation:

In trigonal pyramidal molecule  like molecule of ammonia , the vector some of intra- molecular dipole moment is not zero because the bonds are not symmetrically oriented . In other molecules , bonds are symmetrically oriented in space so the vector sum of all the internal dipole moment  vectors cancel each other to make total dipole moment zero.