Answer: d and f block transition metals (e.g., Pd, La) absorbing H 2 into lattice gaps.
- A d and f block transition metals (e.g., Pd, La) absorbing H<sub>2</sub> into lattice gaps
- B Alkali metals forming stoichiometric ionic hydride salts according to conventional understanding
- C Non-metals forming covalent molecular hydrides in routine practice overall
- D Noble gases trapping hydrogen within clathrate cages in most cases under typical conditions
Correct answer: A. d and f block transition metals (e.g., Pd, La) absorbing H<sub>2</sub> into lattice gaps
Explanation: Transition and lanthanide metals can absorb large amounts of H<sub>2</sub> into interstitial (gap) sites in their crystal lattices.
Each water molecule's O-H bonds (covalent, solid) can hydrogen-bond (dashed) to neighbouring molecules, forming an extended network responsible for water's unusually high boiling point and density anomaly.
Concept context
The simplest and most abundant element in the universe. Study its unique position in the periodic table, isotopes (protium, deuterium, tritium), properties of water and hydrogen peroxide, and industrial uses.