I'm sure that many of you kidz have had the opportunity to inhale helium and hear your voice go up several pitches like Alvin the chipmunk. Sulfur hexafluoride is heavier than air: what do you think will happen to your voice if you inhale it? If helium eventually leaves your lungs because it can easily be breathed out, how will you get the SH6 out? Hint: you have to use your head.
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