If you don’t want to buy a tank, you can use the same equipment that is found in all balloon stores. Just find a large bowl, fill it with water, turn on the faucet and plug it into a wall socket. These can be purchased at hardware stores or can be found on auction sites like ...
Our surrounding is filled with air. ... Now it is known that the density of hydrogen and helium is lighter than that of air. So, if a balloon is filled with