JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Hydrogen

Hydrogen is held safely and reversibly when it is absorbed into the lattice of a metal or an intermetallic compound as a solid hydride, taking up hydrogen at moderate pressure and giving it back on warming. Of the species listed, the intermetallic $\mathrm{NaN}{\mathrm{i}}_5$ is the one that soaks up hydrogen to form a hydride phase $\mathrm{NaN}{\mathrm{i}}_5{\mathrm{H}}_{\mathrm{x}}$, so the compound that raises the efficiency of a hydrogen-storage tank is $\mathrm{NaN}{\mathrm{i}}_5$.