Why do coloured leaves photosynthesise when they are not green in colour?

Why are halogens coloured?

The wavelength of green colour in air and violet colour in water are 5381 Å and 3042 Å respectively. If the wavelength of green colour in water is the same as the wavelength of violet colour in air, find its value. (Assume that refractive index for green and violet colour is approximately same)

The bronze colour of leaves is due to the deficiency of

What colouration do roans possess? Why?