Question

Gold numbers of protective colloids $A, B, C$ and $D$ are $0.50,0.01,0.10$ and $0.005$ respectively. The correct order of their protective power is

• A. $ D< A< C< B $
• B. $ C< B< D< A $
• C. $ A< C< B< D $
• D. $ B< D< A< C $

Answer 1

Answer: (C)

Smaller the value of gold number, greater will be-protective power of the protective colloid.
Protective power of a colloid $\propto \frac{1}{\text { gold number }}$
Hence, the correct order is $A< C< B< D$.