How do ortho and para hydrogen differ from each other?

The basic principle of the hydrogen economy is the transportation and storage of energy in the form of liquid or gaseous hydrogen. Which property of hydrogen may be useful for this purpose? Support your answer with a chemical equation if required.

Which hydride among the following is less stable?

Saline hydrides are known to react with water violently producing fire. Can $CO_2$,a well-known fire extinguisher,be used in this case? Explain.

$TiH_{1.73}$ is an example of

The conversion of atomic hydrogen into ordinary hydrogen is: