(i) How do you expect the metallic hydrides to be useful for hydrogen storage ? (ii) Write a note about ortho water and para water.

(i) How do you expect the metallic hydrides to be useful for hydrogen

1.	(i) How do you expect the metallic hydrides to be useful for hydrogen storage ? (ii) Write a note about ortho water and para water.
Answer» Solution :(i) In metallic hydrides, hydrogen is absorbed as H-atoms. Due to the absortion of H atoms the metal lattice expands and become unstable. Thus, when metallic hydride is heated, it decomposes to form hydrogen and finely divided metal. The hydrogen evolved can be used as fuel. (ii) 1. Water exists in SPACE in the interstellar clouds, in proto - planetary disks, in the comets and ICY satellites of the solar system, and on the earth. 2. In particular, ortho-to-para RATIO (OPR) of water in space has recently received attention. Like hydrogen, water can be classified into ortho-`H_(2)O` and para-`H_(2)O`, in which the directions are antiparallel. 3. At the low temperature conditions of Earth (300K), the OPR of `H_(2)O` is 3. 4. At low temperature below `(LT 50 K)` the amount of para-`H_(2)O` increases. It is known that the OPR of water in interstellar clouds and comets has more para-`H_(2)O` (OPR = 2.5) than on Earth.