Question

rainbow is a pure spectrum or impure spectrum

Answer 1

hey mate here is yoyr ans
The main difference though is that a prism has flat surfaces, leading to apure spectrum, while a raindrop has a round surface, leading to an impure spectrum. ... As this comparison makes obvious, a rainbow is not a pure spectrum. The colors of a rainbow are more blended together and washed out.
hope it helps u

Answer 2

hey mate here is ur ans

Rainbow is an impure spectrum
The colors of a rainbow are more blended together and washed out that means u can't distinguish between the boundary of the two color bands

the water droplets has dust and gases in it
and the spherical shape of rain drops makes the impure spectrum

if u want a pure spectrum u must keep the prism in the minimum deviation

hope it helps you frnd