Helium gas is used in a balloon vendor.
Helium
to keep the balloon floating
helium gas
The balloon with krypton gas has a higher density than the balloon with argon gas.
the gas takes the shape and size of the balloon
propane
A hot air balloon is normally powered with propane. Other than that, it is just ordinary air used inside the balloon.
Helium gas is pumped into a balloon.
The gas is hot air.
This depends on many variables. What is the weight of the notebook, what is the diameter of the balloon, what material is used for the balloon, what gas is used to fill the balloon, what is the weight of the material that is attached to the balloon and the notebook, is this taking place in earth's atmosphere, or somewhere else. There are several other minor variables, as well. And do remember, the balloon must be filled with a gas that is lighter than the surrounding medium!
Hydrogen is used. Sorry. Just regular air is used in a hot air balloon, it is heated which makes it lighter and less dense and therefore provide lift. Hence the name hot air balloon. Hydrogen is used in a gas balloon.