Question

Which of the following colloids is a positively charged colloid?

• A. Hydrated metallic oxides like $A{l}_2{O}_3.x{H}_{2}O$
• B. Metals, e.g., copper, silver, gold sols.
• C. Sols of starch, gum, gelatin, clay, charcoal, etc
• D. Acid dye stuffs, e.g., eosin

Answer 1

The correct option is A Hydrated metallic oxides like $A{l}_2{O}_3.x{H}_{2}O$

Colloidal particles always carry an electric charge. The nature of this charge is the same on all the particles in a given colloidal solution and may be either positive or negative. Hydrated metallic oxide like $A{l}_2{O}_3.x{H}_{2}O$ is an example of positively charged colloid whereas metals, e.g., copper, silver, gold sols, sols of starch, gum, gelatin, clay, charcoal, etc and acid dye stuffs, e.g., eosin form negatively charged colloid.