The change in color when acetone is placed on the wing is due to the difference between the indices of refraction of acetone and air. Consider light of some particular color. In acetone,

A. The frequency of the light is less than in air.

B. The frequency of the light is greater than in air.

C. The wavelength of the light is less than in air.

D. The wavelength of the light is greater than in air.

Option B and Option C

Explanation:

As we know that the wavelength of light is dependent on its speed. In fact the wavelength of light is directly proportional to the speed of the light. If the speed increases, the wavelength will also increase. While moving from air to acetone the speed of light reduces, and hence the wavelength reduces.

Wavelength is inversely proportional to the frequency. In acetone, the wavelength of light reduces, thus the frequency must increase and it should be higher than the frequency of light in air.

Option B and C are correct