Which is the best description of the cause of sound waves? a. a decrease in pressure
b. one object bumping into another
c. molecules becoming electrically charged
d. a vibration in material causing a vibration in an adjacent area

the answer is d

Explanation:

When we hear something, we are sensing the vibrations in the air. The number of vibrations per second is known as the frequency, measured in Hertz (1 Hz = 1 vibration per second).

well first you need the sample of the temperature and gas level. i couldnt write a hypothesis unless i had some data. i think temperature changes will effect volumes of gas because gas changed into a solid or liquid at specific temperatures.