Fires & CO2 vocabulary

Question or Hint Answer or Word

hydrogen is the/an ___________ lightest gas? heaviest gas? invisible gas? gas that's full of odor?
true or false. CO2 is a compound? true? false?
which of these things would make the most friction i f going down a snowy hill or a regular hill a sled? a book? a match?
which things are fuel? gas? oil? books? water? glass?
a/an ______ uses photosynthesis. plant? animal? human? gas?
you would extinguish a _____ fire? an area of water?
covalent bonds are______ electrons? atoms? Neutrons?