What do you call these sound waves whose frequency is above 20000 hertz

The bubbles in a carbonated soft drink are produced when carbonic acid decomposes to form carbon dioxide and water. in a closed system, this equilibrium exists as why does a carbonated soft drink lose carbonation when the container is left open? a.water evaporates, which favors the formation of h2co3. b.pressure decreases, which favors the formation of h2co3. c.the open container warms up, which causes more gas to escape. d.co2is removed, which favors the formation of h2co3.