Question

Question: Which of the following molecules absorbs a longer wavelength of UV light?

Short answer

Answer

A

Step-by-step solution

UV light

The UV light falls between 200 nm and 400 nm. The radiation belonging to this region is colorless due to its very low wavelength.

Effect of conjugation on wavelength  

The conjugation increases the resonance, which decreases the energy and increases the wavelength

Explanation

Compound A has a longer wavelength of UV light due to the presence of more conjugated double bonds.

Conjugated double bond of A

Compound B has a shorter wavelength due to a less conjugated double bond.

Conjugated double bond of B