Question

1. which electromagnetic wave means \below red\ in latin?

radio
x - ray
microwave
infrared

Explanation:

The word "infra" in Latin means "below". Infrared electromagnetic waves have wavelengths longer than those of visible red light, so "infrared" can be thought of as "below red" (in terms of the visible light spectrum's red end). Radio waves have much longer wavelengths than infrared, X - rays have much shorter wavelengths (higher energy), and microwaves have wavelengths longer than infrared but the etymology does not match "below red".

Answer:

infrared