Complete the following statements:

When the sun is setting, the light from it has to travel a ...............thickness of the earth's atmosphere and only ........... wavelength ........... light is able to reach us. Sunset is therefore .......

The sky appears blue because some of the blue component of sunlight is scattered by:

Sunset is red because at that time the light coming from the sun has to travel:

In an experiment to study the scattering of light by passing a beam of white light through a colloidal solution of sulphur in a transparent glass tank :

(a) Which colour is observed from the front of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset ?

(b) Which colour is observed from the sides of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset ?

Explain why, when the sun is overhead at noon, it appears white, but when the same sun is near the horizon at sunset, it appears red.