Hydrogen

4. Hydrogen is used to turn liquid _____.
5. Hydrogen is a pollutant-____ fuel.
7. 1 in 6000 _________ atoms in deuterium.
10. Hydrogen forms ______ hydrides with alkali metals and alkaline earth metals.
11. Carbon dioxide is removed as the ______ flow through a basic solution.
12. Hydrogen is produced when _______ and steam react at 1100 degrees Celsius over a nickel catalyst.
14. Methanol is an __________ solvent.
16. Most hydrogen is _______.
18. Large-scale production of hydrogen currently begins with _____ fuels.
19. In a heavy water reactor the ________ used to make the fuel doesn't have to be enriched.
21. Hydrogen forms covalent _______ hydrides with nonmetals.

1. How often is hydrogen found on Earth in an uncombined state?
2. Electrolysis of _______ produces the purest hydrogen.
3. The initial cost of spending of separating the heavy water from light water is offset by the _____ cost of the uranium fuel.
6. In a hydrogen _______, hydrogen would replace fossils fuels as the energy source for heating, transportation, and industrial process.
8. The other stable isotope is _________.
9. What does formaldehyde make?
13. Hydrides are powerful _________ agents.
15. How much hydrogen produced in the U.S. is used to synthesize the covalent binary compound ammonia?
17. _______ was discovered in 1934.
20. In the future, green ______ may produce hydrogen in the presence of sunlight.