1. What is the chemical symbol for the element hydrogen?
  2. Is helium or hydrogen the most abundant gas in the universe?
  3. Which is the lightest gas, helium or hydrogen?
  4. Where on Earth will you find most of the hydrogen?
  5. What is the difference between blue hydrogen and green hydrogen?
  6. Is hydrogen expensive to produce?
  7. Which four planets are mainly formed from hydrogen?
  8. Hydrogen can be use in pipes existing gas pipelines, true or false?
  9. Apart from an alternative to fossil fuels, name one other use for hydrogen.
  10. Where is hydrogen on the Periodic Table?


  1. H
  2. Hydrogen is the most abundant gas, helium comes second.
  3. Hydrogen is the lightest gas.
  4. The major location of hydrogen is in water.
  5. Blue hydrogen is created from fossil sources, where the carbon emissions are captured and stored. Green hydrogen is made from non-fossil sources.
  6. Green hydrogen is 2-3 times more expensive than blue hydrogen which is produced from fossil fuels in combination with carbon capture and storage (CCS). The production cost for green hydrogen is determined by the renewable electricity price and the investment cost of the electrolyser which splits the hydrogen out from the water.
  7. Jupiter, Saturn, Uranus and Neptune.
  8. True and false. If the pipe is made from polyethylene, the hydrogen can be pumped safely. If the pipe is made from steel, the small hydrogen molecules will escape.
  9. Making ammonia, hydrogenation of fats and oils, methanol production, rocket fuel, welding, production of hydrochloric acid, reduction of metallic ores.
  10. It comes first as it only has one electron and the number of electrons largely determines an element’s position on the Periodic Table.