It has to do with lighting. Read the article link to see what I mean. Hope this helps.
Technically if you mix all of the colours you will get white, as white when broken apart becomes all colours. However, the reality is you will get a messy muddied blackish colour.
no becuz rainbows can keep goin i dnt think they ever stop
Red Orange Yellow Green Blue Violet
A very mucky brownish gray color.