Which statement describes hydrogen storage chemically combined in hydride form?

• A. Stored as liquid and cooled to -423F
• B. Compressed and stored with pressures of 3600, 5000 and 10,000 psi
• C. Chemically combined in hydride form
• D. Stored in microscopic pores of carbon nanotubes

Answer: (C)

Storing hydrogen as a hydride means hydrogen is chemically bound within a solid compound, typically a metal hydride, so hydrogen becomes part of the material’s chemical structure rather than existing as a separate gas or liquid. This bond-based storage is different from physical forms where hydrogen is simply contained under pressure as a gas or kept as a cryogenic liquid. In hydride storage, hydrogen is released when the material undergoes dehydrogenation through heating or a chemical reaction that shifts the balance, rather than by just letting a gas escape. The statement describing hydrogen chemically combined in hydride form captures this idea of chemical bonding in a solid compound. The other options describe physical storage methods—liquefying hydrogen at extremely low temperatures, compressing hydrogen gas at high pressures, or storing hydrogen on surfaces in porous materials—rather than chemical bonding in a hydride.