Question

A sound wave traveling eastward through air
causes the air molecules to
(1) vibrate east and west
(2) vibrate north and south
(3) move eastward, only
(4) move northward, only

Answer 1

1 - Vibrate east and west

Sound waves are longitudinal waves, that means the vibrations are parallel to the direction of energy transfer. If the energy transfer is going East, then the vibrations will be East and West creating compressions and rarefactions in the air.