Question

some information about rainbow.

Answer 1

After the rain a number of small droplets of water remain suspended in the air. Each drop acts as a small prism. When sunlight falls on these drops the white light spills into seven colours. The dispersed light from a large number of drops forms a continuous band of seven colours. 
This coloured band is called a RAINBOW.

Answer 2

rainbow consists of 7 colours. They are as follows:
Violet,Indigo,Blue,Green,Yellow,Orange,Red
Rainbow is an arch of colours in the sky,caused by the sun shining through water droplets in the atmosphere.