How/why does the density of an object change when heated?

Which statement about sound is not true? a. air particles travel with sound waves. b. sound waves cannot travel through a vacuum. c. sound waves exist even if no one hears them. d. air particles vibrate along the path of a sound wave.

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Consider this initial-rate data at a certain temperature for the reaction described by