True or false: White light is a mix of colours.

Yes, this is true and you can demonstrate this fact by splitting light using a prism to create a rainbow. This happens because the prism refracts the different wavelengths of visible light each by slightly different amounts. Thus, white light is sort of a catch all term for the all the light in the visible region of the electromagnetic spectrum, and we all it that because it appears white to our eyes when all the colours are mixed together.

True. The white light is mix of waves with different wavelengths.

True! White light is all the colours mixed together. In science, we can split or disperse the white light in a prism and see all the colours, is red, orange, yellow, green, blue, violet! Black is the ABSENSE of light!