Facts
Because helium is less dense than normal air, when inhaled from a source such as a helium balloon it briefly changes the sound of a person's voice, making it much sound much higher. However, breathing in too much helium can be very dangerous, potentially choking people due to a lack of oxygen.
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Facts
Helium has a lifting force of around one gram per liter. A balloon that holds 10 liters of helium should therefore lift an object weighing 10 grams. Unfortunately you'll need around 5000 of these balloons if you weigh around 50kgs and want to get off the ground.
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