To do this experiment, you need to dip your hands in water. Then, put your hands in bubble mixture with hydrogen. Then ask someone to light the bubbles. Then dip your hands in water and then dry them.
Here are some safety tips: Hold your hands as flat as you can when you are picking up the bubbles. Pick the bubbles up slowly. When the bubbles are picked up, if you curve your hands a bit, the bubbles will float away. Put goggles on because the fire might burn your eyes.
Burning hydrogen doesn't produce smoke. It produces water vapour. If vehicles ran on hydrogen, it wouldn't produce a lot of smoke.
Helium is a rare gas. If you breathe in helium, your voice becomes funny and you get a bit dizzy. Sometimes you can faint. So be careful with helium if you breathe it in.
If you put helium in a balloon it floats away too. If you light helium, the helium won't burn.