Why is the air in the stratosphere stable? A denser air lies above this dense air
B cooler air lies above warmer air
C warmer air lies above cooler air
D both a and b

Compare these two waves : a. the blue wave has a higher pitch, but the orange wave is louder. b.the blue and orange waves have the same volume, but the blue wave has a higher pitch. c.the blue and orange waves have the same pitch, but the blue wave is louder. d.the orange wave has a higher pitch, but the blue wave is louder.

Light waves can move through , but they travel fastest when they move through a(n) .

Before it was launched, a helium-filled balloon had a pressure of 201 kpa at a temperature of 27°c. at an altitude of 15,000 m, the pressure had decreased to 2.5 kpa and the temperature had dropped to -14 °c. the volume of the balloon increased to 59.3 m3. what is the original volume of the balloon? 13 m3 0.85 m3 0.077 m3 1.17 m3