In trans-1,2-dichloroethylene, which of the following vibrational modes is IR inactive?

The first Stokes line of a rotational Raman spectrum is observed at 12.96 cm-1. Considering the rigid rotor approximation, the rotational constant is given by:

For an anharmonic diatomic molecule, the vibrational energy levels are written as: εv = ωe(v + 1/2) - ωexe(v + 1/2)2 [cm-1] The highest possible vibrational quantum number (v) is given by: