**Which can adsorb a larger volume of hydrogen?**

A) Colloidal solution of palladium
B) Finely divided nickel
C) Finely divided platinum
D) Colloidal Fe(OH)3

To determine which substance can adsorb a larger volume of hydrogen, we need to consider their physical and chemical properties that enable hydrogen adsorption. Let's analyze each option:

**A) Colloidal solution of palladium:**
Palladium is known to exhibit a high affinity for hydrogen due to its ability to absorb and retain large quantities of the gas. When palladium is in a colloidal solution form, it has a high surface area, which further enhances its adsorption capacity. The numerous small particles present in the colloidal solution provide a larger surface area for hydrogen molecules to interact with, allowing for a larger volume of hydrogen to be adsorbed.

**B) Finely divided nickel:**
Finely divided nickel also possesses a high affinity for hydrogen and can adsorb a significant amount of the gas. Similar to palladium, the high surface area of finely divided nickel increases its adsorption capacity. The smaller particles allow for more hydrogen molecules to interact with the surface of the nickel, resulting in a larger volume of hydrogen being adsorbed.

**C) Finely divided platinum:**
Finely divided platinum also exhibits a strong affinity for hydrogen and can adsorb a considerable quantity of the gas. The high surface area provided by the finely divided particles enables platinum to interact with a large number of hydrogen molecules, leading to a higher volume of hydrogen adsorption.

**D) Colloidal Fe(OH)3:**
Colloidal Fe(OH)3, also known as colloidal iron(III) hydroxide, is not known for its significant hydrogen adsorption capacity. While it may have some ability to adsorb hydrogen, it is generally not as effective as the other options mentioned above. The lower surface area and different chemical properties of colloidal Fe(OH)3 limit its ability to adsorb a large volume of hydrogen.

In conclusion, the substances that can adsorb a larger volume of hydrogen are A) colloidal solution of palladium, B) finely divided nickel, and C) finely divided platinum. These materials have higher surface areas and exhibit strong affinities for hydrogen, allowing for a greater amount of hydrogen to be adsorbed compared to colloidal Fe(OH)3.

Absorption is a bulk effect whereas adsorption is a surface effect. Colloids, having large surface areas for a given volume, are excellent at adsorption.
 Palladium is the best in absorbing hydrogen gas. The rate of absorption is  affected by the physical condition of the substance. Palladium has great degree of subdivision so it has more efficient occlusive capacity.