Question

write two properties common to all electromagnetic radiation

Answer 1

Electromagnetic radiation can travel through empty space.  Most other types of waves must travel through some sort of substance.  For example, sound waves need either a gas, solid, or liquid to pass through in order to be heard.

The speed of light is always a constant.  (Speed of light : 2.99792458 x 108 m s-1)

Answer 2

1) Electromagnetic waves are propagated by oscillating electric and magnetic fields oscillating at right angles to each other.
2) Electromagnetic waves are not deflected by electric or magnetic field.