Explanation:

UV absorption spectra are useful for identifying functional groups and aromaticity in organic compounds. In the case of acetone, the absorption at max 279 nm is due to the n-π* transition.

Heading: Explanation of n-π* transition

The n-π* transition occurs when an electron in a non-bonding orbital (n) transitions to an anti-bonding π* orbital. This transition is associated with the absorption of UV light in the range of 180-280 nm.

Heading: Role of acetone in n-π* transition

In acetone, the n-π* transition is due to the lone pair of electrons on the oxygen atom interacting with the π* antibonding orbitals of the carbonyl group. This interaction causes the electrons to transition from the non-bonding orbital to the antibonding orbital, resulting in the absorption of UV light at 279 nm.

Heading: Significance of UV absorption spectra

UV absorption spectra can provide important information about the electronic structure of organic compounds. The position and intensity of the absorption bands can be used to identify functional groups, determine the degree of unsaturation, and even quantify the concentration of a compound in a mixture.

Heading: Conclusion

In conclusion, the absorption at max 279 nm in the UV spectrum of acetone is due to the n-π* transition. This transition is associated with the interaction between the lone pair of electrons on the oxygen atom and the π* antibonding orbitals of the carbonyl group. UV absorption spectra are useful for identifying functional groups and providing information about the electronic structure of organic compounds.