Question

if sunlight is composed of seven diffferent colours, then why does the sun look orange-yellow?

Answer 1

The colour of the Sun is an effect of the Earth's atmosphere. Sunlight is practically made up of seven colours and is white, but refraction will scatter the visible light frequencies, and more in the blue end (which produces the blue daylight sky). More of the yellow and red colors reach your eyes, especially when the Sun is near the horizon and the light has to pass through much more of the atmosphere.