Soap bubbles viewed in white light show colours. The phenomenon responsible for it is following

The correct answer is Interference.

Key Points

•  The Colour of the soap bubble is due to the interference of reflected light from the film-air interface.

• In the case of soap bubble made of a transparent soap film with plane parallel faces separated by a distance t as shown in the figure below.

• Suppose a parallel beam of light is incident on the film at an angle i. The wave is divided into two parts at the upper surface, one is reflected and the other is refracted.
• The refracted part enters into two parts; one is transmitted out of the film and the other is reflected back.
• Multiple reflections and refraction take place and a number of reflected waves, as well as transmitted waves, are sent by the film.

• The interference of reflected light waves in the thin film results in the formation of either Constructive or Destructive.

Additional Information 

• Scattering: The intensity of scattered light is inversely proportional to the fourth power of the wavelength; provided the scatter is smaller in size than the wavelength of light
• Dispersion: The white light gets split into constituent "VIBGYOR".
• Diffraction: It is spreading out of any wave due to an encounter with any obstacle.