(c) Butadiene (C4H6) has two isomers, the cis and the trans forms, which are shown below: (i) How many normal vibrations do each of these molecules possess? (ii) Presuming only one isomer is present, use a group theoretical analysis to determine how IR spectroscopy in the CH stretching region could establish if it is the cis or trans isomer (note that both isomers are planar molecules). (iii) Could IR spectroscopy in the C=C stretching region be used to distinguish between the cis and trans isomers? [Hint: it is not necessary to do a group theoretical analysis to answer this particular part of the question.] (iv) What would be seen in the CH stretching region of the Raman spectra of the two isomers? (v) How would the spectra change if all the H atoms in both molecules were replaced with D atoms