Me i’m having trouble and i don’t understand

If we compare and contrast electromagnetic waves with sound waves, all but one statement is true. that is a) sound waves require a medium to travel while electromagnetic waves do not. b) electromagnetic waves can travel through the vacuum of space while sound waves cannot. c) electromagnetic waves must have a medium in which to travel, but sound waves can travel anywhere. eliminate d) sound waves must bounce off of matter in order to travel while electromagnetic waves do not require matter to be present.

Avariable that is not being directly tested during an experiment should be changed varied experimented controlled

Which sample at stp has the same number of atoms as 18 liters of ne at stp