Explanation:

Introduction
Mesityl oxide and its isomer have a different molecular structure, which affects their electronic transitions and UV-Vis spectra.

UV-Vis Spectra
UV-Vis spectra provide information about the electronic transitions in a molecule. The absorption bands in UV-Vis spectra correspond to the energy required to promote an electron from a ground-state orbital to an excited-state orbital. The position and intensity of these bands depend on the molecular structure and the nature of the electronic transitions.

Mesityl Oxide
Mesityl oxide has a conjugated system of double bonds, which allows for electronic transitions that give rise to absorption bands in the UV-Vis spectrum. The two bands observed at 230 nm and 327 nm correspond to π→π* transitions of the double bonds and n→π* transitions of the carbonyl group, respectively. The intensity of these bands is influenced by factors such as the extent of conjugation, the nature of the substituents, and the solvent used.

Isomer of Mesityl Oxide
The isomer of mesityl oxide does not show any bands above 210 nm because it lacks a conjugated system of double bonds. The double bond in this molecule is isolated and is not part of a conjugated system. Therefore, there are no π→π* transitions that give rise to absorption bands in the UV-Vis spectrum. The absence of absorption bands above 210 nm is consistent with the lack of electronic transitions in the molecule.

Conclusion
In conclusion, the different electronic structures of mesityl oxide and its isomer result in different UV-Vis spectra. Mesityl oxide has a conjugated system of double bonds that gives rise to absorption bands at 230 nm and 327 nm, while the isomer lacks a conjugated system and does not show any bands above 210 nm.