Answer:
The CO2 Extinguisher Cannisters contain carbon dioxide in liquid form, and when the extinguisher is let off the liquid is released into the air neutralising the oxygen that the fire is feeding on, disabling the fires ability to spread.
4.2 hours, do 315 miles / 75 miles per hour
I'm pretty sure all 4 are subatomic particles but if i had to guess i'd be Photons