State two properties of electromagnetic waves. How can we show that em waves carry momentum?

Properties of electromagnetic waves are:

i) In an electromagnetic wave, the electric field vector and the magnetic field vector are always perpendicular to each other and both are perpendicular to the direction of propagation. They do not require any medium to propagate and travel with a constant velocity
of 3x10⁸ m s^-1.

ii) They can be polarized and show properties of interference and diffraction.

Electromagnetic waves are constituted by photons of energy E and velocity c. Thus the momentum(p) is given by:

To illustrate this, consider an electric charge on a plane perpendicular to the electromagnetic waves. When these waves hit the plane, they set the electric charge in motion (by transfer of energy and exchange of momentum). Hence, they carry both energy and momentum.