(A) (i) Dispersion of white light refers to the separation of white light into its component colours when it passes through a prism or any other refracting medium. This happens because different colours of light have different wavelengths and refract at slightly different angles as they pass through the medium.
(ii) When white light passes through a glass prism, the colour that bends the most is violet because it has the shortest wavelength and is refracted the most. On the other hand, the colour that bends the least is red because it has the longest wavelength and is refracted the least. The other colours of the spectrum (in order of increasing wavelength) are indigo, blue, green, yellow and orange.
(B) A rainbow is a natural phenomenon that occurs when sunlight is refracted, reflected and dispersed in water droplets in the air. It appears as a circular arc of different colours, with red on the outer edge and violet on the inner edge. A rainbow can only be seen when the sun is behind the observer and the rain is in front of the observer. The seven colours of the rainbow are red, orange, yellow, green, blue indigo and violet and they appear in that order from the outer to the inner edge.