A small helium tank measures about two feet (60 cm) high. Yet it can fill over 50 balloons! How can such a small tank contain enough helium to fill so many balloons?

The tank is able to contain enough helium to fill over 50 balloons because the gas contained in the small helium tank has been compressed under pressure which then expands dues to less pressure in the balloons and it then fills up the balloons .

The particles in a gas are relatively far apart filling up the volume of their containers and possess kinetic energy, being only restricted by the walls of their containers. Thus gases, do not have a specific volume or shape.

Because of the spaces between gas particles, gases can be compressed under great pressure to occupy less volume, and can also expand under reduced pressure.

The particles of gas in the helium tank are compressed under pressure, thus they occupy less volume.

In a balloon however, the particles are under less pressure, and as such quickly fill up the balloon.

Therefore, the gas contained in the helium tank can fill up over 50 balloons.

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Explanation:

Gases have very unique property, they fill up and take up the shape of any medium they find themselves in.

They expand out in all directions indefinitely. Their particles are random and lack no internal attraction.

the answer is barium and copper bromide