Answer: Electromagnetic waves can travel through a vacuum; mechanical waves require a medium. Electromagnetic waves are visible; mechanical waves are invisible. Electromagnetic waves always reflect; mechanical waves always refract.
Explanation: There are two types of waves:
Mechanical waves: these waves consist of oscillations of the particles in a medium. Therefore, they can only propagates if there is a medium. Examples of mechanical waves are sound waves
Electromagnetic waves: they consist of oscillations of the electric and the magnetic field in a plane perpendicular to the direction of motion the wave. All electromagnetic waves travel in a vacuum always at the same speed, the speed of light: . They are the only types of waves that do not require a medium to propagate, so they can also travel through a vacuum.
We can now analyze the different statements:
Both types of waves require a medium. --> FALSE. Electromagnetic waves do not require a medium.
Both types of waves have a frequency. --> TRUE. All waves are characterized by their frequency, which is the number of complete oscillations per second.
Both types of waves transmit matter. --> FALSE. Waves transmit energy, but not matter.
Both types of waves have a pitch --> FALSE. Pitch tells how we perceive the frequency of a sound wave: but electromagnetic waves are not sound waves, so this statement is false.