The balloon could be filled with hydrogen or helium, depending on the price and whether it burns. In general, helium is more expensive than hydrogen. Helium is a safe inert gas that does not support combustion and is not flammable, while hydrogen is a more reactive gas that is flammable and explosive.
Here's how to determine whether a balloon is filled with hydrogen or helium:
1. Look at the price
Both helium and hydrogen can make a balloon float, but the price is very different, usually helium is more expensive than hydrogen. A 40-liter tank of Bulus helium costs about 1,600 yuan, and a tank of hydrogen costs about 80 yuan.
2. See if it can burn
Helium is a safe, inert gas that is neither combustive nor flammable. Hydrogen is more active, flammable and explosive, and can not be in contact with open flame.
Many street vendors now use cheap hydrogen balloons to reduce costs, so you have to be careful when buying them, and it is better to buy your own balloons and inflate them with helium, which is safer.