What two factors principally affect the sped of sound in a gas?

1) temperature

2) the relative humidity of the air

Explanation:

1) Temperature of the gas primarily affects the speed of sound in a gas.

2) Air is a mixture of gases and water vapor, the humidity of the air will have an effect on the speed of sound.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.