What is the common feature among the waves associated with all of the orbital shells?

Which of the statements about waves is true? a. in longitudinal waves, particles move perpendicular to the direction the wave is traveling.b. both transverse and longitudinal waves can travel through water c. electromagnetic waves are a type of longitudinal waves.d. in a transverse wave, particles move parallel to the direction the wave is traveling.

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above