Last one brainliest on this one to I will give it to u

it is helium

Step-by-step explanation:Sound travels faster in helium than it does in ordinary air. (heluim atoms are less massive than oxygen or nitrogen molecules and so for a given amount of heat energy available (temperature) they will fly about quicker and carry a disturbance more rapidly ie sound).

In a sound wave the product of wavelength and frequency is a constant and is equal to the sound speed. I'm afraid this isn't a very rigorous answer but, using this relationship, we know the local sound speed is increased and given that the wavelengths of the noises produced are more or less unchanged (presumably since the dominant wavelengths produced in speech depend mainly on the geometry and the dimensions of the throat during a particular articulation) the frequency or pitch will therefore rise.

20

step-by-step explanation:

126 maybe. sorry