Why only helium is filled in balloons??
Hydrogen and nitrogen are also light in weight.then why we don't use these gases??
The exploding balloons demonstrate that nothing can be taken for granted in science. If you buy a balloon from a vendor, it’s probably filled with helium. Helium is a gas like air; in fact, air has some helium in it. But helium is lighter than air. If you take the same volume of air and helium and weight them on a scale, the helium will weight less. This is because helium is less dense. Because helium is lighter than air, a helium balloon rises. Hydrogen and nitrogen are another gas lighter than air; it is even lighter than helium. Hydrogen and nitrogen are not used in balloons and this demonstration shows why.
Helium is a special gas called a Noble Gas, which means it doesn’t burn. When a match is held near a helium-filled balloon, the balloon pops. That’s it. But when a match is held near a hydrogen-filled balloon: BOOM! a real explosion. This is because hydrogen burns very easily. It combines with oxygen to make water vapor. Even though both balloons look the same from the outside, there may be something very different on the inside