.

1. Science is full of fascinating facts. Example:

Sodium - you can't consume it, most probably you won't survive. Chlorine-inhalation of chlorine is highly toxic. But when they both mix, produces salt, necessary for our daily consumption.

Hydrogen- it burns itself. Oxygen-without it, nothing can burn. But when they both react, produces water, best fire extinguisher.

Edit: Thank you for the upvote!!. Getting so many comments as CO2 is the best fire extinguisher, but do you all have CO2 cylinders at home? My answer was about fascinating facts of science, like how hydrogen and oxygen changes their properties after reaction, not comparing between different fire extinguishers.