Which of the following rays is not an electromagnetic wave?

Beta rays also known as beta radiation is obtained through the emission of an electron.  Beta rays are not electromagnetic waves because they are charged particles and are capable of getting deflected by the magnetic field. These rays are not pure energy as a photon.

Electromagnetic spectrum consists of radio waves, microwaves, infrared waves, visible spectrum, ultraviolet waves, X-rays and gamma rays. 

Heat rays are also known as infrared radiation.