Question

Is sound wave in a solid electromagnetic or transverse?

Answer 1

If you take the case of  a rail on a railway track.  The sound wave travels along the length of the rail.  This is mechanical wave.  The particles of the medium  - steel - vibrate along the direction of propagation.  So not transverse.  They are longitudinal waves or pressure waves.

If you take the case of musical instruments.  The wires vibrate. They cause vibrations in air. They are longitudinal mechanical waves.

Sound waves are mechanical and not  electromagnetic.

Answer 2

Sound travels through longitudinal waves. Sound travels through transversal waves in 90 degrees. The other main type of wave is the transverse wave, in which the displacements of the medium are at right angles to the direction of propagation.