hi i couldnt think of an experiment for this one but i saw this video of a hydrogen rocket on your references and thought it was pretty cool

Hong Kong relays heavy on fossil fuels how can we optimise green energy

How can we use hydrogen power

by showing a miniature rocket experiment to show hydrogen fuel can be used in actual rockets or in aeroplanes.

using pipets as our rockets we will use the hydrogen we produced to show how easy and green hydrogen fuel is and modify a bbq lighter and collect hydrogen gas 4/6 in pipet and add oxygen gas 2/6 in quantities to test if our hydrogen could possibly be used for actual rockets.

If the mini rockets preform well we can hypothesise that hydrogen gas would work as rocket fuel

We could have airplanes made out of hydrogen gas.