Humans can hear frequencies up to approximately 20,000 Hz, while dogs can hear frequencies up to around 60,000 Hz. What sound frequency would you expect to be emitted by a dog whistle, which can be heard by dogs but not by humans?

Why does karst topography exist in some geographic location? a. few climates have enough oxygen b. most regions have rock layers other than limestone c. in most regions, the soil is too thin d. the water is too acidic enough in most places