The answer should be altitude
Like you might have studied. Heated hair expands while colder air contracts. So, the sound isn't able to move as efficiently in cold air than it would in warmer air.
Answer:
Sewage treatment generally involves three stages, called primary, secondary and tertiary treatment. Primary treatment consists of temporarily holding the sewage in a quiescent basin where heavy solids can settle to the bottom while oil, grease and lighter solids float to the surface.
Explanation:
Hope that helps:)
