Answer the following questions for the MOs of 1,3-butadiene:
d. Which MO is the HOMO and which is the LUMO in the excited state?
e. What is the relationship between the HOMO and the LUMO and symmetric and antisymmetric orbitals?

4-Methylbenzylidene camphor (4-MBC) is used by the cosmetic industry for its ability to protect the skin against UV-B radiation. Circle the part of the molecule that you theorize is responsible for its effects on UV light.

A solution was prepared using 0.0010 g of an unknown steroid (of molecular weight around 255) in 100 mL of ethanol. Some of this solution was placed in a 1-cm cell, and the UV spectrum was measured. This solution was found to have λ_max = 235 nm, with A = 0.74.

(a) Compute the value of the molar absorptivity at 235 nm.

(b) Which of the following compounds might give this spectrum?