Walking and Climbing

Literally and metaphorically that's a question of density.

Not to mention a BANG loud enough to be heard for miles...

The maximum mixed volume of hydrogen and oxygen I can "explode" in a lab is 30 cubic centimetres.  Even then...and getting the kids to put fingers in their ears, there is usually a shocked silence afterwards

Strictly speaking...not quite..that was hydrogen burning in excess of air - and as air is 78% nitrogen

this is hydrogen burning in oxygen....andthis

couldnt resist it...and

this

At our school the teachers did a pop bottle rocket to explain the hydrogen/oxygen thing. They did that for two classes of chemistry to watch. But what was best was our inorganic chemistry teacher who occasionally got bored teaching us so sometimes he'd stop teaching and ask us what we'd like to talk about. That could be anything from a footie match to what his uni wasa like or anything at all. We did learn some chemistry too like he did the hydrogen pop bottle rocket, demonstrated a chip pan fire under the building and a few other stuff. Did you know caesium wrapped up in bread and fed to seagulls is an interesting way to control said seagul population?!!!

BTW the answer is gas is more dispersed than the equivalent elements combined in the form of liquid. IIRC gas is more dispersed than liquid which is moree dispersed than solids. Theonly one I can think of which this is not true is water since solid water (ice) floats on ice it clearly showing that it has lower density than water. Although ice is actually made up of solid, liquid and gas phases of H2O. Interesting stuff that and very important for life. BTW the densest H2O is at about 4 degrees C I got taught.