The correct descending order of the electro magnetic waves according to their wavelengths is

1. UV-rays, γ-rays, microwaves, infrared
2. infrared, microwaves, UV-rays, γ-rays
3. γ-rays, UV rays, Infrared rays, microwaves
4. microwaves, infrared rays, UV rays, γ-rays

microwaves > infrared rays > UV rays > γ-rays

Reason — The order of electro magnetic waves in terms of decreasing wavelengths is : microwaves > infrared rays > UV rays > γ-rays