Question

state the difference of the colour of the sun observed during sunrise /sunset and noon. Give reason for each

Answer 1

during sun rise sun is away from earth so most of the light having shorter wavelength scatters earlier and longer wavelenhth red colour comes to the eye of the observer
and for sunset is visa versa

Answer 2

Sun appears red at sunrise and sunset : At sunrise and sunset, sun is closer to the horizon. The sunlight passes through denser layer of air and covers larger distance before reaching our eyes. Most of the blue light gets scattered. The light that reaches our red. That is why the sun appears red at sunrise. 

At noon, the sun is overhead. The sunlight passes through rares layers of air and covers shorter distance before reaching our eye. So, almost all colours of light are scattered equally. Hence the sun appears white