Hydrogen gas is the least dense substance in the world, at 0.08988g/cc.  Hydrogen solid is the most dense substance in the world, at 70.6g/cc.

Random Facts

• Every year about 98% of atoms in your body are replaced.
  Human Facts
• The mask used by Michael Myers in the original film 'Halloween' was actually a Captain Kirk mask painted white.
  Entertainment Facts
• Wearing headphones for just an hour will increase the bacteria in your ear by 700 times.
  Human Facts
• The Hawaiian alphabet has 12 letters.
  Word and Language Facts
• Tigers have striped skin, not just striped fur.
  Animal Facts
• The word 'queue' is the only word in the English language that is still pronounced the same way when the last four letters are removed.
  Word and Language Facts
• It is physically impossible for pigs to look up into the sky.
  Animal Facts
• Humans and dolphins are the only species that have sex for pleasure.
  Animal Facts