Concept:Hydrogen gas absorbed in solid palladium forms an interstitial solid solution, so the solute is gas and the solvent is solid.
Explanation:Palladium is a solid transition metal.
It can absorb a large volume of hydrogen gas into its crystal lattice.
The hydrogen atoms occupy the interstitial spaces between palladium atoms.
In this solution, palladium acts as the solvent because it is present in a larger amount and remains solid.
Hydrogen is the solute because it is the smaller component, initially present as a gas and then dissolved as atoms.
Hence, the solution is classified as gas solute dissolved in solid solvent.
Answer:Option A: Gas as solute and solid as solvent.